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Newton had a fun way to approximate general roots...
#17
(09-13-2022, 06:59 PM)Jack Wrote: bplus, the log and exp are done in double precision as part of the first approximation, I don't see a problem with that, also what if you want to take the root of a huge number?
for example
31415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989 ^ (1/3)
I have split the first approximation to allow for larger exponents than double allows
instead of t2 = Log(t) / p + Log(10) * ex / p, do

t2 = Log(t) / p
t2 = Exp(t2)
str2fp ry, Str$(t2) 'convert the double t2 to decfloat in ry
t = Log(10) * ex / p
t2 = Exp(t - Fix(t))
str2fp tmp, Str$(t2) 'convert the double t2 to decfloat in tmp
fpmul ry, ry, tmp, prec
str2fp tmp, "2.7182818284590452353602874713527"
fpipow tmp, tmp, Fix(t), 24
fpmul ry, ry, tmp, prec

basically it does the following
here the value of x is split into a fractional part and a base 10 exponent, so if x = 3.14159e2000 then frac_x=3.14159 and ex=2000
first approximation =
exp(log(frac_x) / p) * exp(fix(ex/p)) * exp(frac(ex/p)) 'here frac is the fractional part of expression

I tried this out with my string math Newton method and in 300 iterations got:

3155367569301821867326519405336421207498251961314999997901193388809739079012897744887631254739292007907947433618484758481627548989501719089220482459948775432816342410555282540612960501433021296640960423450227920209938211887719077129428385543361947758023983184697480787087966223432486682721792221472648796720202642738747343051078071241.1117071041521464114467665711102448773294129185086168601317116963185840973781697545265065162416345701960981890223171963919001466208647505186686688214089040608753503438578563616725892063902904031115393739976591472520070482477893735495911139188769943267929855525949446230204126900153007732827612762319412945242149116780371747470206338539664157784440481347746085970295430028320843441298257423953610577963963949129300606668858848121206003518186891859385615602534889346333454621516856947153242770387046690053536732721613842936129950903162157547041886847070767874866662505338899454778151212530761556961371244325097728839734967258370200043173928708494473297733210411715984593169290517702411869427839950464670060349819760147612661909441546958517699224130778087110443124358261707076171153443438495681205599420721937187851525696893584001727191760274149236224353644424090955353510261465763750332840754794617508053971409028884388363664964752877980030249110322873254352734271785400456477991026383527973330108928903271467756263321278894522083868571618282515818461381943038367779552617133598991116964887655701157012974067987940699411399501229096552888963789307921632996569433309896456328377371297669783052361470311472211

Qube that answer and we get:

31415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000603499005139366862799701780720158591410366351998129151511119525687388749502797039682234552131747456613792066033484465152215809841804291448971276204046929625487309185281858037724869323483434152864858964962994001836657061656106352620454324148283376076399490345337954627590065806114045867049052326544516109184526712585489406993500328338398198408461889212477292574781998715931861578961152941542876486164940515418178077033851931868282699884213321398226844876483100577921117201183608525521876800029277538167845818865776704783972229142090194304398125633856083142539675220841343105833147855969761212488889068336718053011348609919308647064997293549061755379552770378475493541876952345373313969858594175197125353608135184548862740674157528924231852223405208449504748388921445240958214690995810105025065423855693672088622863753117064768322664890025536617798854536218488816791848538821446950866269851253733911386611361910540274644323253232874172081162346914699996142266777798954022070123212527344388924719217925914386633353072987330648829157403550708115027223200044807883656469347663655876969648987101678645940222022831480079400768418299325559664895684045999255371982432620239090677375662502747701542703358133368428665082731835860910000665702147427296276045564628750796535846183280725239965866623509246666148961072282514122502077078743852037518058193632425928923084786277291885961300536668681338313110684273723118785419227857031392445436462972677644980466766435357102613205226750122405761223701269699916778576569554050536346411140767860976270187630791949828546645057030248690468772912088596795560468444063512633185518997406170826723372775379876955170922403298311843012025288476087485121551879800953646194661776016049207809926994868956877276788933438172018961190857263702091141726455945984960349569883378976481691201424503846716470549678954871666104627769881334536069365184512548629329824854143087775243885679288308641597452616789909800095812019114437954817600548618681574588627849594754143169473932594598937914117840979460016740619770688788545236109486266753724433791353227792899002288778552124706192536713772490236607545877818633549777809122533461987954188757373396000734054021074761847398893009527051762586890797854285944214083130177511207817184310434788177482556340875733459076305930401101867740557129021454597311093304249357526453113349715688916583994808262174737596388796185189688284300995099114815929770078432405884155920175427576979092016431903239034848212944617640707267844664353544109998979530824698138597632254927543828879612566189320793914511582305163073365737983758502482677721478732753892280786074576136564428824243375592483381200215324298908739000854267257562524746199375548144863137863318489017325830040905355143109220371392913354012472788837467428130745760495771708768099321048804173582693961219013757642478754104803966634627299465120902984446399248781478306905405997541726676409883232468635606493479953311325416216747257599651982333093941048126219978507387638390288595752818405351078630965605875184189176621134721573958750820153788398487490359386406455645497953416129931


Woohoo! So somewhere less than 300 iterations gets the job done. Just cut off the crap afet the decimal point and it's a match.

Please note that doing this routine allowed me to find one bug in my new division routine, so DON'T try running this in the older post in this thread. Here is the one I used...

Code: (Select All)
'WIDTH 120, 42
'_SCREENMOVE 0, 0
$CONSOLE:ONLY
' Treebeard's String Math +-*/
CONST neg$ = "-"
CONST negative = -1
CONST positive = 1
CONST asc0 = 48
CONST dp_tree$ = "."
CONST zero$ = "0"
CONST one$ = "1"
CONST two$ = "2"
CONST three$ = "3"
CONST four$ = "4"
CONST five$ = "5"
CONST False = 0
CONST True = -1
CONST basechr = "@"
CONST basesep$ = ","
CONST maxlongdig = 8
CONST emem = 32
CONST memget = 0
CONST memput = 1
CONST defaultdigits = 30
CONST maxmem = 35
CONST maxstack = 10
CONST minconst = 30
CONST maxconst = 35
CONST pimem = 30
CONST pi2mem = 31
CONST phimem = 33
CONST ln10mem = 34
CONST ln2mem = 35
CONST memclr = 2

'useful shared stuff, initialize these in bInit()
DIM SHARED errormsg$, abortmsg$, Error$, bmem$(maxmem), out$
DIM SHARED zmem$(maxstack), cname$(maxconst)
DIM SHARED bncpath$, prmcntfile$
DIM SHARED digits%, zstack%

'Prime count table data
DIM maxprmcnt%
DIM prmcnt&
digits% = 16
'--------------------------------------------

DIM SHARED limit&&, betatest%: betatest% = 0 '-1
n$ = "31415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989"
limit&& = LEN(n$) + 8
digits% = limit&&: PRINT n$, LEN(n$): PRINT

REM Newton's Square Root Algorithm expanded for general roots...
REM a - ((a) ^ root - n) / (root * a ^ (root - 1))

DO
    INPUT "Enter 1 for Pete's string math or 2 for Treebeard's: "; choice
    IF choice < 1 OR choice > 2 THEN RUN

    a$ = "314159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808651328230664709384460955058223172535940812848111745028410270193852110555964462294895493038196442881097566593344612847564823378678316527120190914564856692346034861045432664821339360726024914127372458700660631558817488152092096"
    ''LINE INPUT "Number: "; n$
    ''LINE INPUT "Root:   "; root$
    root$ = "3"
    DO
        temp1$ = sm_sub$(root$, "1")
        IF betatest% = 1 THEN PRINT "root - 1 ="; temp1$
        i&& = 1: temp2$ = a$
        DO UNTIL LTRIM$(STR$(i&&)) = temp1$
            i&& = i&& + 1
            IF choice = 1 THEN
                temp2$ = sm_mult$(a$, temp2$)
            ELSE
                bMul a$, temp2$, x$: temp2$ = x$
            END IF
        LOOP
        IF betatest% = 1 THEN PRINT "a$, temp2$: "; a$; " * "; temp2$
        IF choice = 1 THEN
            sqrt_divisor$ = sm_mult$(temp2$, root$)
        ELSE
            bMul temp2$, root$, sqrt_divisor$
        END IF
        IF betatest% = 1 THEN PRINT "divisor$  = "; sqrt_divisor$
        temp2$ = a$: i&& = 1
        DO UNTIL LTRIM$(STR$(i&&)) = root$
            i&& = i&& + 1
            IF choice = 1 THEN
                temp2$ = sm_mult$(a$, temp2$)
            ELSE
                bMul a$, temp2$, x$: temp2$ = x$
            END IF
            ''COLOR 8: PRINT i&&, temp2$: COLOR 7: SLEEP
        LOOP
        IF betatest% = 1 THEN PRINT "a^root, n$: "; temp2$; " - "; n$
        IF choice = 1 THEN
            sqrt_dividend$ = sm_sub$(temp2$, n$)
        ELSE
            bSub temp2$, n$, sqrt_dividend$
        END IF
        IF betatest% = 1 THEN PRINT "dividend$ = "; sqrt_dividend$
        IF choice = 1 THEN
            temp1$ = sm_div$(sqrt_dividend$, sqrt_divisor$)
        ELSE
            bDiv sqrt_dividend$, sqrt_divisor$, temp1$
        END IF
        IF betatest% = 1 THEN COLOR 15: PRINT "a$ = "; a$; " - "; "temp1$ = "; temp1$, sqrt_dividend$, sqrt_divisor$: COLOR 7
        IF betatest% = 1 THEN PRINT "a$, dividend$, divisor$: "; a$; " - "; sqrt_dividend$; " / "; sqrt_divisor$
        IF choice = 1 THEN
            a$ = sm_sub$(a$, temp1$)
        ELSE
            bSub a$, temp1$, x$: a$ = x$
        END IF
        PRINT "Iteration"; v + 1; a$: PRINT
        v = v + 1
    LOOP UNTIL v = 300
    _CLIPBOARD$ = a$
    PRINT STRING$(_WIDTH, "-"): PRINT
    v = 0
LOOP

SUB sm_greater_lesser (stringmatha$, stringmathb$, gl%)
    compa$ = stringmatha$: compb$ = stringmathb$ ' So original variables do not get changed.
    DO
        WHILE -1 ' Falx loop.
            IF gl% = 2 THEN EXIT WHILE ' For bypassing sign and decimal adjustments when only positive non-decimal numbers are being evaluated.
            ' Remove trailing zeros after a decimal point.
            IF INSTR(compa$, ".") THEN
                DO UNTIL RIGHT$(compa$, 1) <> "0" AND RIGHT$(compa$, 1) <> "." AND RIGHT$(compa$, 1) <> "-"
                    compa$ = MID$(compa$, 1, LEN(compa$) - 1)
                LOOP
            END IF
            IF INSTR(compb$, ".") THEN
                DO UNTIL RIGHT$(compb$, 1) <> "0" AND RIGHT$(compb$, 1) <> "." AND RIGHT$(compb$, 1) <> "-"
                    compb$ = MID$(compb$, 1, LEN(compb$) - 1)
                LOOP
            END IF

            IF MID$(compa$, 1, 2) = "-0" OR compa$ = "" OR compa$ = "-" THEN compa$ = "0"
            IF MID$(compb$, 1, 2) = "-0" OR compb$ = "" OR compb$ = "-" THEN compb$ = "0"

            ' A - and +
            j% = 0: k% = 0
            IF LEFT$(compa$, 1) = "-" THEN j% = -1
            IF LEFT$(compb$, 1) = "-" THEN k% = -1
            IF k% = 0 AND j% THEN gl% = -1: EXIT DO
            IF j% = 0 AND k% THEN gl% = 1: EXIT DO

            j&& = INSTR(compa$, ".")
            k&& = INSTR(compb$, ".")

            ' A starting decimal and non-decimal.
            IF j&& = 0 AND k&& = 1 THEN
                IF compa$ = "0" THEN gl% = -1 ELSE gl% = 1
                EXIT DO
            END IF
            IF k&& = 0 AND j&& = 1 THEN
                IF compb$ = "0" THEN gl% = 1 ELSE gl% = -1
                EXIT DO
            END IF

            ' remove decimals and align.
            j2&& = 0: k2&& = 0
            IF j&& <> 0 OR k&& <> 0 THEN
                IF j&& THEN compa$ = MID$(compa$, 1, INSTR(compa$, ".") - 1) + MID$(compa$, INSTR(compa$, ".") + 1): j2&& = LEN(compa$) - j&& + 1
                IF k&& THEN compb$ = MID$(compb$, 1, INSTR(compb$, ".") - 1) + MID$(compb$, INSTR(compb$, ".") + 1): k2&& = LEN(compb$) - k&& + 1
                compa$ = compa$ + STRING$(k2&& - j2&&, "0")
                compb$ = compb$ + STRING$(j2&& - k2&&, "0")
            END IF
            EXIT WHILE
        WEND

        ' Remove leading zeros if any.
        DO UNTIL LEFT$(compa$, 1) <> "0"
            compa$ = MID$(compa$, 2)
        LOOP
        IF compa$ = "" THEN compa$ = "0"
        DO UNTIL LEFT$(compb$, 1) <> "0"
            compb$ = MID$(compb$, 2)
        LOOP
        IF compb$ = "" THEN compb$ = "0"

        ' Both positive or both negative whole numbers.

        SELECT CASE LEN(compa$)
            CASE IS < LEN(compb$)
                gl% = -1
            CASE IS = LEN(compb$)
                IF compa$ = compb$ THEN
                    gl% = 0
                ELSEIF compa$ > compb$ THEN gl% = 1
                ELSEIF compa$ < compb$ THEN gl% = -1
                END IF
            CASE IS > LEN(compb$)
                gl% = 1
        END SELECT
        EXIT DO
    LOOP
    '''PRINT "<> gl% ="; gl%; "   "; compa$; "   "; compb$; "   "; stringmatha$; "   "; stringmathb$ '''''''
    '''IF gl% = 1 AND VAL(compa$) <= VAL(compb$) THEN BEEP: SLEEP ''''''
    '''IF gl% = -1 AND VAL(compa$) >= VAL(compb$) THEN BEEP: SLEEP '''''
END SUB

SUB sm_add_subtract_router (stringmatha$, operator$, stringmathb$, runningtotal$)
    DIM AS _INTEGER64 a, c, s
    a1$ = stringmatha$: b1$ = stringmathb$
    s = 18: i&& = 0: c = 0

    a$ = stringmatha$: b$ = stringmathb$: op$ = operator$

    IF op$ = "-" THEN
        IF LEFT$(b$, 1) = "-" THEN b$ = MID$(b$, 2) ELSE b$ = "-" + b$
    END IF

    IF INSTR(a$, ".") <> 0 OR INSTR(b$, ".") <> 0 THEN
        decimal% = -1
        IF INSTR(a$, ".") <> 0 THEN
            dec_a&& = LEN(MID$(a$, INSTR(a$, ".") + 1))
            a$ = MID$(a$, 1, INSTR(a$, ".") - 1) + MID$(a$, INSTR(a$, ".") + 1)
        END IF
        IF INSTR(b$, ".") <> 0 THEN
            dec_b&& = LEN(MID$(b$, INSTR(b$, ".") + 1))
            b$ = MID$(b$, 1, INSTR(b$, ".") - 1) + MID$(b$, INSTR(b$, ".") + 1)
        END IF
        ' Line up decimal places by inserting trailing zeros.
        IF dec_b&& > dec_a&& THEN
            j&& = dec_b&&
            a$ = a$ + STRING$(dec_b&& - dec_a&&, "0")
        ELSE
            j&& = dec_a&&
            b$ = b$ + STRING$(dec_a&& - dec_b&&, "0")
        END IF
    END IF

    IF LEFT$(a$, 1) = "-" OR LEFT$(b$, 1) = "-" THEN
        IF LEFT$(a$, 1) = "-" AND LEFT$(b$, 1) = "-" THEN
            sign$ = "": a$ = MID$(a$, 2): b$ = MID$(b$, 2)
        ELSE
            IF LEFT$(a$, 1) = "-" THEN a$ = MID$(a$, 2): sign_a$ = "-"
            IF LEFT$(b$, 1) = "-" THEN b$ = MID$(b$, 2): sign_b$ = "-"

            IF LEFT$(a1$, 1) = "-" THEN a1_x$ = MID$(a1$, 2) ELSE a1_x$ = a1$
            IF LEFT$(b1$, 1) = "-" THEN b1_x$ = MID$(b1$, 2) ELSE b1_x$ = b1$

            sm_greater_lesser a1_x$, b1_x$, gl%

            IF gl% < 0 THEN
                IF LEN(sign_b$) THEN sign$ = "-": SWAP a$, b$
            ELSE
                IF LEN(sign_a$) THEN sign$ = "-": SWAP sign_a$, sign_b$
            END IF
        END IF
    END IF

    z$ = ""
    ' Addition and subtraction of digits.
    DO
        i&& = i&& + s
        x1$ = MID$(a$, LEN(a$) - i&& + 1, s)
        x2$ = MID$(b$, LEN(b$) - i&& + 1, s)
        IF LEN(x2$) > LEN(x1$) THEN SWAP x1$, x2$
        a = VAL(sign_a$ + x1$) + VAL(sign_b$ + x2$) + c
        IF x1$ + x2$ = "" AND c = 0 THEN EXIT DO
        c = 0
        IF a > VAL(STRING$(s, "9")) THEN a = a - 10 ^ s: c = 1
        IF a < 0 THEN a = a + 10 ^ s: c = -1 ' a will never be less than 0.
        tmp$ = LTRIM$(STR$(a))
        z$ = STRING$(LEN(x1$) - LEN(tmp$), "0") + tmp$ + z$
    LOOP

    IF decimal% THEN
        z$ = MID$(z$, 1, LEN(z$) - j&&) + "." + MID$(z$, LEN(z$) - j&& + 1)
    END IF

    ' Remove any leading zeros.
    DO
        IF LEFT$(z$, 1) = "0" THEN z$ = MID$(z$, 2) ELSE EXIT DO
    LOOP

    IF z$ = "" OR z$ = "0" THEN z$ = "0" ELSE z$ = LEFT$(sign$, 1) + z$

    runningtotal$ = z$

    sign$ = "": sign_a$ = "": sign_b$ = "": i&& = 0: j&& = 0: decimal% = 0: c = 0
END SUB

FUNCTION sm_validate (validate$)
    sm_validate = 0: vsn_negcnt& = 0: vsn_poscnt& = 0: vsn_depresent& = 0: decimalcnt& = 0: vsn_numberpresent& = 0: vsn_zerospresent& = 0
    IF LEFT$(validate$, 1) = "-" THEN validate$ = MID$(validate$, 2): sm_sign$ = "-" ELSE sm_sign$ = ""
    WHILE -1 ' Falx loop.
        IF LEFT$(validate$, 1) = "+" THEN IF sm_sign$ <> "-" THEN validate$ = MID$(validate$, 2) ELSE validate$ = "invalid number": EXIT WHILE
        IF INSTR(UCASE$(validate$), "D") OR INSTR(UCASE$(validate$), "E") THEN ' Evaluate for Scientific Notation.
            FOR sm_i& = 1 TO LEN(validate$)
                validatenum$ = MID$(UCASE$(validate$), sm_i&, 1)
                SELECT CASE validatenum$
                    CASE "+"
                        IF vsn_depresent& THEN vsn_poscnt& = vsn_poscnt& + 1 ELSE validate$ = "invalid number": EXIT WHILE
                    CASE "-"
                        IF vsn_depresent& THEN vsn_negcnt& = vsn_negcnt& + 1 ELSE validate$ = "invalid number": EXIT WHILE
                    CASE "0" TO "9"
                        vsn_numberpresent& = -1
                    CASE "D", "E"
                        vsn_depresent& = vsn_depresent& + 1
                        IF decimalcnt& = 0 AND sm_i& <> 2 OR vsn_depresent& > 1 OR vsn_numberpresent& = 0 OR vsn_negcnt& > 1 OR vsn_poscnt& > 1 OR vsn_negcnt& = 1 AND vsn_poscnt& >= 1 THEN vsn_numberpresent& = 0: EXIT FOR
                        vsn_numberpresent& = 0
                        MID$(validate$, sm_i&, 1) = "e" ' Standardize
                    CASE "."
                        decimalcnt& = decimalcnt& + 1
                        IF sm_i& <> 2 THEN vsn_numberpresent& = 0: EXIT FOR
                    CASE ELSE
                        vsn_numberpresent& = 0: EXIT FOR
                END SELECT
            NEXT
            IF decimalcnt& = 0 THEN validate$ = MID$(validate$, 1, 1) + "." + MID$(validate$, 2) ' Standardize "."
            IF vsn_numberpresent& = 0 OR vsn_negcnt& = 1 AND vsn_poscnt& = 1 OR decimalcnt& > 1 OR INSTR(validate$, ".") <> 2 THEN validate$ = "invalid number": EXIT WHILE
            vsn_depresent& = INSTR(validate$, "e")
            sm_x$ = MID$(validate$, vsn_depresent& + 1, 1) ' Standardize exponent "+" these two lines.
            IF sm_x$ <> "+" AND sm_x$ <> "-" THEN validate$ = MID$(validate$, 1, vsn_depresent&) + "+" + MID$(validate$, vsn_depresent& + 1)
            IF MID$(validate$, vsn_depresent& + 2, 1) = "0" THEN
                IF MID$(validate$, vsn_depresent& + 3, 1) <> "" THEN validate$ = "invalid number": EXIT WHILE ' No leading zeros allowed in exponent notation.
            END IF
            jjed& = INSTR(validate$, "e") ' Get position of notation.
            valexpside$ = MID$(validate$, jjed&) ' These two lines break up into number and notation
            validate$ = MID$(validate$, 1, jjed& - 1) ' validate$ is +- single digit whole number, decimal point and decimal number. valexpside$ is notation, sign and exponent.
            DO UNTIL RIGHT$(validate$, 1) <> "0" ' Remove any trailing zeros for number. Example 1.0d3 or 1.0000d3, etc.
                validate$ = MID$(validate$, 1, LEN(validate$) - 1)
            LOOP
            IF VAL(MID$(validate$, 1, INSTR(validate$, ".") - 1)) = 0 THEN
                IF RIGHT$(validate$, 1) = "." THEN
                    validate$ = "0.e+0" ' Handles all types of zero entries.
                ELSE
                    validate$ = "invalid number": EXIT WHILE
                END IF
                EXIT WHILE
            END IF
            validate$ = sm_sign$ + validate$ + valexpside$
            EXIT WHILE
        ELSE
            FOR sm_i& = 1 TO LEN(validate$)
                validatenum$ = MID$(validate$, sm_i&, 1)
                SELECT CASE validatenum$
                    CASE "."
                        decimalcnt& = decimalcnt& + 1
                    CASE "0"
                        vsn_zerospresent& = -1
                    CASE "1" TO "9"
                        vsn_numberpresent& = -1
                    CASE "$"
                    CASE ELSE
                        validate$ = "invalid number": EXIT WHILE
                END SELECT
            NEXT
            IF decimalcnt& > 1 OR vsn_negcnt& > 1 OR vsn_poscnt& > 1 OR vsn_negcnt& >= 1 AND vsn_poscnt& >= 1 THEN
                validate$ = "invalid number": EXIT WHILE
            END IF
            REM IF INSTR(validate$, "$") THEN GOSUB currency_validate
            IF INSTR(validate$, ",") THEN
                REM GOSUB comma_validation
                IF validate$ = "invalid number" THEN EXIT WHILE
                REM GOSUB comma_removal
            END IF
            IF RIGHT$(validate$, 1) = "." THEN validate$ = MID$(validate$, 1, LEN(validate$) - 1)
            DO UNTIL LEFT$(validate$, 1) <> "0" ' Strip off any leading zeros.
                validate$ = MID$(validate$, 2)
            LOOP
            validate$ = sm_sign$ + validate$
            IF INSTR(validate$, ".") THEN
                DO UNTIL RIGHT$(validate$, 1) <> "0" ' Strip off any trailing zeros in a decimal.
                    validate$ = MID$(validate$, 1, LEN(validate$) - 1)
                LOOP
            END IF
            IF RIGHT$(validate$, 1) = "." THEN validate$ = MID$(validate$, 1, LEN(validate$) - 1)
            IF vsn_numberpresent& = 0 THEN
                IF vsn_zerospresent& THEN
                    validate$ = "0"
                ELSE
                    validate$ = "invalid number"
                END IF
            END IF
        END IF
        EXIT WHILE
    WEND
    IF validate$ = "invalid number" THEN sm_validate = 1 ELSE sm_validate = 0
END FUNCTION

FUNCTION sm_add$ (stringmatha$, stringmathb$)
    operator$ = "+"
    sm_add_subtract_router stringmatha$, operator$, stringmathb$, runningtotal$
    sm_add$ = runningtotal$
END FUNCTION

FUNCTION sm_sub$ (stringmatha$, stringmathb$)
    operator$ = "-"
    sm_add_subtract_router stringmatha$, operator$, stringmathb$, runningtotal$
    sm_sub$ = runningtotal$
END FUNCTION

FUNCTION sm_mult$ (stringmatha$, stringmathb$)
    DIM AS _INTEGER64 a, c, aa, cc, s, ss
    z$ = "": sign$ = "": mult&& = 0: h&& = 0: i&& = 0: j&& = 0: c = 0: decimal% = 0
    zz$ = "": ii&& = 0: jj&& = 0
    s = 8: ss = 18

    a$ = stringmatha$: b$ = stringmathb$

    IF INSTR(a$, "-") <> 0 OR INSTR(b$, "-") <> 0 THEN
        IF INSTR(a$, "-") <> 0 AND INSTR(b$, "-") <> 0 THEN
            a$ = MID$(a$, 2): b$ = MID$(b$, 2)
        ELSE
            IF INSTR(a$, "-") <> 0 THEN a$ = MID$(a$, 2) ELSE b$ = MID$(b$, 2)
            sign$ = "-"
        END IF
    END IF

    IF INSTR(a$, ".") <> 0 OR INSTR(b$, ".") <> 0 THEN
        decimal% = -1
        IF INSTR(a$, ".") <> 0 THEN
            dec_a&& = LEN(MID$(a$, INSTR(a$, ".") + 1))
            a$ = MID$(a$, 1, INSTR(a$, ".") - 1) + MID$(a$, INSTR(a$, ".") + 1)
        END IF
        IF INSTR(b$, ".") <> 0 THEN
            dec_b&& = LEN(MID$(b$, INSTR(b$, ".") + 1))
            b$ = MID$(b$, 1, INSTR(b$, ".") - 1) + MID$(b$, INSTR(b$, ".") + 1)
        END IF
    END IF

    IF LEN(a$) < LEN(b$) THEN SWAP a$, b$ ' Needed so x1$ is always the largest for leading zero replacements.
    ' Multiplication of digits.
    DO
        h&& = h&& + s: i&& = 0
        x2$ = MID$(b$, LEN(b$) - h&& + 1, s)
        DO
            i&& = i&& + s
            x1$ = MID$(a$, LEN(a$) - i&& + 1, s)
            a = VAL(x1$) * VAL(x2$) + c
            c = 0
            tmp$ = LTRIM$(STR$(a))
            IF LEN(tmp$) > s THEN c = VAL(MID$(tmp$, 1, LEN(tmp$) - s)): tmp$ = MID$(tmp$, LEN(tmp$) - s + 1)
            z$ = STRING$(LEN(x1$) - LEN(tmp$), "0") + tmp$ + z$
        LOOP UNTIL i&& >= LEN(a$) AND c = 0

        jj&& = jj&& + 1

        IF jj&& > 1 THEN
            ii&& = 0: cc = 0
            aa$ = holdaa$
            bb$ = z$ + STRING$((jj&& - 1) * s, "0")
            ' Addition only of digits.
            DO
                ii&& = ii&& + ss
                xx1$ = MID$(aa$, LEN(aa$) - ii&& + 1, ss)
                xx2$ = MID$(bb$, LEN(bb$) - ii&& + 1, ss)
                IF LEN(xx1$) < LEN(xx2$) THEN SWAP xx1$, xx2$
                aa = VAL(xx1$) + VAL(xx2$) + cc
                IF xx1$ + xx2$ = "" AND cc = 0 THEN EXIT DO ' Prevents leading zeros.
                cc = 0
                IF aa > VAL(STRING$(ss, "9")) THEN aa = aa - 10 ^ ss: cc = 1
                tmp$ = LTRIM$(STR$(aa))
                zz$ = STRING$(LEN(xx1$) - LEN(tmp$), "0") + tmp$ + zz$
            LOOP

            DO WHILE LEFT$(zz$, 1) = "0"
                IF LEFT$(zz$, 1) = "0" THEN zz$ = MID$(zz$, 2)
            LOOP
            IF zz$ = "" THEN zz$ = "0"

            holdaa$ = zz$
        ELSE
            holdaa$ = z$ + STRING$(jj&& - 1, "0")
        END IF

        z$ = "": zz$ = ""

    LOOP UNTIL h&& >= LEN(b$)

    z$ = holdaa$

    IF decimal% THEN
        DO UNTIL LEN(z$) >= dec_a&& + dec_b&&
            z$ = "0" + z$
        LOOP

        z$ = MID$(z$, 0, LEN(z$) - (dec_a&& + dec_b&& - 1)) + "." + MID$(z$, LEN(z$) - (dec_a&& + dec_b&&) + 1)

        DO UNTIL RIGHT$(z$, 1) <> "0" AND RIGHT$(z$, 1) <> "."
            z$ = MID$(z$, 1, LEN(z$) - 1)
        LOOP
    END IF

    IF STRING$(LEN(z$), "0") = z$ OR z$ = "" OR z$ = "0" THEN z$ = "0" ELSE z$ = sign$ + z$

    decimal% = 0: sign$ = ""

    runningtotal$ = z$
    sm_mult$ = z$
END FUNCTION

FUNCTION sm_div$ (stringmatha$, stringmathb$)
    hold_stringmatha$ = stringmatha$: hold_stringmathb$ = stringmathb$
    q$ = "": divisor$ = stringmathb$: dividend$ = stringmatha$
    DO ' Falx loop.
        'Strip off neg(s) and determine quotent sign.
        IF LEFT$(divisor$, 1) = "-" THEN divisor$ = MID$(divisor$, 2): q$ = "-"
        IF LEFT$(dividend$, 1) = "-" THEN dividend$ = MID$(dividend$, 2): IF q$ = "-" THEN q$ = "" ELSE q$ = "-"

        ' Quick results for divisor 1 or 0.
        IF dividend$ = "0" THEN q$ = "0": EXIT DO
        IF divisor$ = "1" THEN q$ = dividend$: EXIT DO
        IF divisor$ = "0" THEN q$ = "Division by zero not possible.": EXIT DO

        ' Determine decimal direction. -1 to left, +1 to right.
        gl% = 0: sm_greater_lesser divisor$, dividend$, gl%
        IF betatest% AND gl% = 1 THEN PRINT divisor$; " > "; dividend$; " Move decimal to the left"
        IF betatest% AND gl% = 0 THEN PRINT divisor$; " = "; dividend$
        IF betatest% AND gl% = -1 THEN PRINT divisor$; " < "; dividend$; " Move deciml to the right."
        IF gl% = 1 THEN ' Divisor is larger than dividend so decimal moves to the left.
            div_decimal% = -1 ' Move decimal point to the left.
        ELSEIF gl% = -1 THEN
            div_decimal% = 1 ' Move decimal point to the right.
        ELSE
            ' Divisor and dividend are the same number.
            q$ = q$ + "1": EXIT DO
        END IF
        divisor_ratio_dividend% = gl%

        ' Strip off decimal point(s) and determine places in these next 2 routines.
        dp&& = 0: dp2&& = 0: j2&& = 0
        temp&& = INSTR(divisor$, ".")
        IF temp&& THEN
            divisor$ = MID$(divisor$, 1, temp&& - 1) + MID$(divisor$, temp&& + 1)
            IF temp&& = 1 THEN
                DO UNTIL LEFT$(divisor$, 1) <> "0" ' Strip off any leading zeros on divisor only.
                    divisor$ = MID$(divisor$, 2)
                    dp&& = dp&& + 1
                LOOP
                dp&& = dp&& + 1
            ELSE
                dp&& = -(temp&& - 2)
            END IF
        ELSE
            dp&& = -(LEN(divisor$) - 1)
        END IF
        temp&& = INSTR(dividend$, ".")
        IF temp&& THEN
            dividend$ = MID$(dividend$, 1, temp&& - 1) + MID$(dividend$, temp&& + 1)
            IF temp&& = 1 THEN
                DO UNTIL LEFT$(dividend$, 1) <> "0" ' Strip off any leading zeros on divisor only.
                    dividend$ = MID$(dividend$, 2)
                    dp2&& = dp2&& + 1
                LOOP
                dp2&& = dp2&& + 1
            ELSE
                dp2&& = -(temp&& - 2)
            END IF
        ELSE
            dp2&& = -(LEN(dividend$) - 1)
        END IF
        IF betatest% THEN COLOR 11: PRINT "Divisor decimal moves "; LTRIM$(STR$(dp&&)); ". Dividend decimal moves"; LTRIM$(STR$(dp2&&)); ". Quotent decimal ABS("; LTRIM$(STR$(dp&&)); " - "; LTRIM$(STR$(dp2&&)); ") =";: COLOR 14: PRINT ABS(dp&& - dp2&&);: COLOR 11: PRINT "+ any adjustment.": COLOR 7
        dp&& = ABS(dp&& - dp2&&)

        IF betatest% THEN PRINT "Divisor 1st# = "; MID$(divisor$, 1, 1); "  Remainder 1st# = "; MID$(dividend$, 1, 1)

        ' Adjust decimal place for instances when divisor is larger than remainder the length of the divisor.
        j% = 0
        IF MID$(divisor$, 1, 1) > MID$(dividend$, 1, 1) THEN
            j% = 1
            IF betatest% THEN PRINT "Larger divisor, so move quotent decimal one place back to: ";: COLOR 14: PRINT LTRIM$(STR$(dp&&)): COLOR 7
        ELSEIF MID$(divisor$, 1, 1) = MID$(dividend$, 1, 1) THEN
            IF LEN(divisor$) = LEN(dividend$) THEN
                IF divisor$ > dividend$ THEN j% = 1
            ELSE
                IF LEN(divisor$) > LEN(dividend$) THEN
                    temp$ = dividend$ + STRING$(LEN(divisor$) - LEN(dividend$), "0")
                ELSE
                    temp$ = MID$(dividend$, 1, LEN(divisor$))
                END IF
                IF divisor$ > temp$ THEN j% = 1
            END IF
            IF j% THEN
                dp&& = dp&& - div_decimal%
                IF betatest% THEN PRINT "Larger divisor than dividend at LEN(divisor$), so move quotent decimal one place back to: ";: COLOR 14: PRINT LTRIM$(STR$(dp&&)): COLOR 7
            ELSE
                IF betatest% THEN PRINT "Smaller divisor than dividend at LEN(divisor$), so no quotent decimal place adjustment needed. Quotent decimal place = ";: COLOR 14: PRINT LTRIM$(STR$(dp&&)): COLOR 7
            END IF
        ELSE
            j% = 0
            IF betatest% THEN PRINT "Smaller divisor, so no quotent decimal place adjustment needed. Quotent decimal place = ";: COLOR 14: PRINT LTRIM$(STR$(dp&&)): COLOR 7
        END IF
        IF j% THEN dp&& = dp&& - div_decimal%

        origdividend$ = dividend$
        ' Determine length of divisor and dividend to begin initial long divison step.
        gl% = 2: sm_greater_lesser divisor$, MID$(dividend$, 1, LEN(divisor$)) + STRING$(LEN(divisor$) - LEN(dividend$), "0"), gl%
        divisor_ratio_dividend% = gl%
        IF gl% = 1 AND MID$(dividend$, 1, 1) <> "0" THEN
            dividend$ = MID$(dividend$, 1, LEN(divisor$) + 1) + STRING$(LEN(divisor$) + 1 - LEN(dividend$), "0")
        ELSE
            dividend$ = MID$(dividend$, 1, LEN(divisor$)) + STRING$(LEN(divisor$) - LEN(dividend$), "0")
        END IF

        ' Long divison loop. Mult and subtraction of dividend and remainder.
        k&& = 0
        IF betatest% THEN PRINT "Begin long divison loop..."
        DO
            SELECT CASE MID$(divisor$, 1, 1)
                CASE IS < MID$(dividend$, 1, 1)
                    adj_rem_len% = 0
                CASE IS = MID$(dividend$, 1, 1)
                    gl% = 2: sm_greater_lesser divisor$, MID$(dividend$, 1, LEN(divisor$)), gl%
                    IF gl% = 1 THEN adj_rem_len% = 1 ELSE adj_rem_len% = 0
                CASE IS > MID$(dividend$, 1, 1)
                    adj_rem_len% = 1
            END SELECT
            IF j2&& = 0 THEN j2&& = LEN(divisor$) + adj_rem_len%
            DO
                IF LEN(divisor$) > LEN(dividend$) THEN
                    w3&& = 0: runningtotal$ = dividend$: stringmathb$ = "0"
                    IF betatest% THEN PRINT: COLOR 3: PRINT "Divisor is larger so "; dividend$; " \ "; divisor$; " =";: COLOR 5: PRINT w3&&: COLOR 7
                    EXIT DO
                END IF
                IF LEN(divisor$) = LEN(dividend$) THEN
                    gl% = 2: sm_greater_lesser divisor$, dividend$, gl%
                    IF gl% = 1 THEN
                        w3&& = 0: runningtotal$ = dividend$: stringmathb$ = "0"
                        IF betatest% THEN COLOR 9: PRINT "Length of divisor is the same as remainder but remainder is smaller so w3&& = ";: COLOR 5: PRINT "0": COLOR 7
                        EXIT DO
                    END IF
                END IF
                SELECT CASE LEN(dividend$)
                    CASE IS > 2
                        w3&& = VAL(MID$(dividend$, 1, 2 + adj_rem_len%)) \ VAL(MID$(divisor$, 1, 2))
                        IF betatest% THEN PRINT MID$(dividend$, 1, 2 + adj_rem_len%); " \ "; MID$(divisor$, 1, 2); " =";
                    CASE ELSE
                        w3&& = VAL(MID$(dividend$, 1, 1 + adj_rem_len%)) \ VAL(MID$(divisor$, 1, 1))
                        IF betatest% THEN PRINT MID$(dividend$, 1, 1 + adj_rem_len%); " \ "; MID$(divisor$, 1, 1); " =";
                END SELECT
                IF betatest% THEN COLOR 5: PRINT " " + LTRIM$(STR$(w3&&));: COLOR 7: PRINT ". Begin mult est. at or one above this number."
                IF w3&& < 9 THEN w3&& = w3&& + 1 ELSE IF w3&& = 10 THEN w3&& = 9
                DO
                    stringmatha$ = divisor$: stringmathb$ = LTRIM$(STR$(w3&&))
                    runningtotal$ = sm_mult$(divisor$, LTRIM$(STR$(w3&&)))
                    gl% = 2: sm_greater_lesser runningtotal$, dividend$, gl%
                    IF gl% <= 0 OR w3&& = 0 THEN EXIT DO
                    IF betatest% THEN COLOR 8: PRINT "Mult loop:"; w3&&; "* "; divisor$; " = "; runningtotal$: COLOR 7
                    w3&& = w3&& - 1
                LOOP
                stringmatha$ = dividend$: stringmathb$ = runningtotal$
                sm_add_subtract_router dividend$, "-", stringmathb$, runningtotal$
                EXIT DO
            LOOP
            IF betatest% THEN PRINT LTRIM$(STR$(w3&&)); " * "; divisor$; " = "; stringmathb$; " | "; stringmatha$; " - "; stringmathb$; " = "; runningtotal$; " Remainder and drop-down = ";
            j2&& = j2&& + 1
            drop$ = "0": MID$(drop$, 1, 1) = MID$(origdividend$, j2&&, 1)
            IF runningtotal$ <> "0" THEN remainder$ = runningtotal$ ELSE remainder$ = ""
            dividend$ = remainder$ + drop$
            w3$ = LTRIM$(STR$(w3&&))
            temp$ = ""
            IF div_decimal% = -1 THEN
                IF dp&& AND k&& = 0 THEN
                    q$ = q$ + "." + STRING$(dp&& - 1, "0")
                    IF w3&& = 0 THEN w3$ = ""
                END IF
            END IF
            IF div_decimal% >= 0 THEN
                IF dp&& = k&& THEN
                    temp$ = "."
                END IF
            END IF
            q$ = q$ + w3$ + temp$
            IF betatest% AND remainder$ = "" THEN betatemp$ = CHR$(34) + CHR$(34) ELSE IF betatest% THEN betatemp$ = remainder$
            IF betatest% AND MID$(origdividend$, j2&&, 1) = "" THEN betatemp2$ = CHR$(34) + CHR$(34) ELSE IF betatest% THEN betatemp2$ = MID$(origdividend$, j2&&, 1)
            IF betatest% THEN PRINT dividend$; " ("; betatemp$; " +  "; drop$; ") at:"; j2&&; "of "; origdividend$; "  Loop"; k&& + 1; "Quotent = ";: COLOR 14, 4: PRINT q$;: COLOR 7, 0: PRINT: SLEEP
            ' Check to terminate
            IF div_decimal% = -1 THEN
                ' Decimal to left.
                IF remainder$ = "" AND MID$(origdividend$, j2&&, 1) = "" OR LEN(q$) >= limit&& THEN EXIT DO
            ELSE
                ' Decimal to right.
                IF remainder$ = "" AND MID$(origdividend$, j2&&, 1) = "" AND k&& >= dp&& OR LEN(q$) >= limit&& THEN EXIT DO
            END IF

            IF INKEY$ = " " THEN EXIT DO
            k&& = k&& + 1
        LOOP
        EXIT DO
    LOOP
    IF RIGHT$(q$, 1) = "." AND divisor$ <> "0" THEN runningtotal$ = MID$(q$, 1, LEN(q$) - 1) ELSE runningtotal$ = q$
    sm_div$ = runningtotal$
    stringmatha$ = hold_stringmatha$: stringmathb$ = hold_stringmathb$
END FUNCTION

FUNCTION sm_sqrt$ (sm_var$)
    oldy$ = "": sqrt$ = "": IF limit&& < 150 THEN custom_limit&& = 150 ELSE custom_limit&& = limit&&
    sqrt_a$ = sm_var$
    IF INSTR(sqrt_a$, ".") THEN
        decx$ = MID$(sqrt_a$, 1, INSTR(sqrt_a$, ".") - 1)
        sqrt_a$ = MID$(sqrt_a$, 1, INSTR(sqrt_a$, ".") - 1) + MID$(sqrt_a$, INSTR(sqrt_a$, ".") + 1)
        IF LEN(sqrt_a$) = 1 THEN sqrt_a$ = sqrt_a$ + "0"
    ELSE
        decx$ = sqrt_a$
    END IF

    j&& = LEN(decx$)

    ' VAL() okay, one character eval.
    IF VAL(RIGHT$(LTRIM$(STR$(j&&)), 1)) / 2 = VAL(RIGHT$(LTRIM$(STR$(j&&)), 1)) \ 2 THEN
        i&& = 1 ' Even number length.
    ELSE
        i&& = 0 ' Odd number length.
    END IF

    DO
        runningtotal$ = sm_sub$(z$, k$) '''''         sm z$, "-", k$, runningtotal$
        z$ = runningtotal$ + (MID$(sqrt_a$, i&&, 2))
        IF LEFT$(z$, 1) = "0" THEN z$ = MID$(z$, 2) ' Remove leading zeros

        oldy$ = ""
        FOR j&& = 1 TO 10
            IF i&& > 1 THEN
                y$ = sm_mult$(sqrt$, "2") '''' sm sqrt$, "*", "2", y$
                y$ = y$ + LTRIM$(STR$(j&&))
            ELSE
                y$ = LTRIM$(STR$(j&&))
            END IF

            runningtotal$ = sm_mult$(y$, LTRIM$(STR$(j&&))) '''''sm y$, "*", LTRIM$(STR$(j&&)), runningtotal$

            sm_greater_lesser runningtotal$, z$, gl%
            IF gl% > -1 THEN
                IF gl% = 0 THEN
                    h% = 0: oldy$ = y$ ' Perfect square division.
                ELSE
                    h% = 1
                END IF
                runningtotal$ = sm_mult$(oldy$, LTRIM$(STR$(j&& - h%))) '''', runningtotal$

                IF STRING$(LEN(z$), "0") = z$ AND runningtotal$ = "0" AND i&& >= LEN(decx$) THEN EXIT DO

                IF dpx&& = 0 THEN ' Limited to && size unless converted to string.
                    IF i&& >= LEN(decx$) THEN
                        dpx&& = INT(LEN(decx$) / 2 + .5)
                        IF dpx&& = 0 THEN dpx&& = -1
                    END IF
                END IF

                IF betatest% < -1 THEN PRINT "Sqrt "; sqrt$; " * 2 = ";: COLOR 2, 0: PRINT LTRIM$(STR$(VAL(sqrt$) * 2));: COLOR 7, 0: PRINT LTRIM$(STR$(j&& - h%)); " * "; LTRIM$(STR$(j&& - h%)); " ="; VAL(oldy$) * (j&& - h%)
                sqrt$ = sqrt$ + LTRIM$(STR$(j&& - h%))

                runningtotal$ = sm_mult$(oldy$, LTRIM$(STR$(j&& - h%))) '''', runningtotal$
                k$ = runningtotal$

                IF betatest% < -1 THEN PRINT "Remainder "; z$; " minus "; k$; " = ";
                EXIT FOR
            END IF
            oldy$ = y$
        NEXT

        i&& = i&& + 2
        IF LEN(z$) >= custom_limit&& THEN EXIT DO
        sqrt_a$ = sqrt_a$ + "00"
    LOOP

    IF dpx&& THEN sqrt$ = MID$(sqrt$, 0, dpx&& + 1) + "." + MID$(sqrt$, dpx&& + 1)
    sm_sqrt$ = sqrt$
END FUNCTION

FUNCTION sm_sqr$ (sm_var$)
    runningtotal$ = sm_mult$(sm_var$, sm_var$)
    sm_sqr$ = runningtotal$
END FUNCTION

FUNCTION sm_div_old$ (stringmatha$, stringmathb$)
    terminating_decimal% = 0: divsign% = 0: divremainder& = 0: divremainder$ = "": divplace& = 0: divplace2& = 0: quotient$ = "": divcarry& = 0
    divbuffer& = LEN(stringmathb$) - LEN(stringmatha$)
    IF divbuffer& < 0 THEN divbuffer& = 0
    d2dividend$ = stringmatha$
    d1divisor$ = stringmathb$
    IF LEFT$(d1divisor$, 1) = "0" AND LEN(d1divisor$) = 1 THEN PRINT "Division by zero not allowed.": divsign% = 0: EXIT FUNCTION
    IF LEFT$(d1divisor$, 1) = "-" THEN divsign% = -1: d1divisor$ = MID$(d1divisor$, 2)
    IF LEFT$(d2dividend$, 1) = "-" THEN
        IF divsign% THEN
            divsign% = 0
        ELSE
            divsign% = -1
        END IF
        d2dividend$ = MID$(d2dividend$, 2)
    END IF
    IF INSTR(d1divisor$, ".") <> 0 THEN
        DO UNTIL RIGHT$(d1divisor$, 1) <> "0"
            d1divisor$ = MID$(d1divisor$, 1, LEN(d1divisor$) - 1) ' Strip off trailing zeros
        LOOP
        divplace& = LEN(d1divisor$) - INSTR(d1divisor$, ".")
        d1divisor$ = MID$(d1divisor$, 1, INSTR(d1divisor$, ".") - 1) + MID$(d1divisor$, INSTR(d1divisor$, ".") + 1) ' Strip off decimal point.
        DO UNTIL LEFT$(d1divisor$, 1) <> "0"
            d1divisor$ = MID$(d1divisor$, 2) ' Strip off leading zeros for divisors smaller than .1
        LOOP
    END IF

    IF INSTR(d2dividend$, ".") <> 0 THEN
        d2dividend$ = d2dividend$ + STRING$(divplace& - LEN(d2dividend$) - INSTR(d2dividend$, "."), "0") ' Add any zeros based on the length of dividend at decimal - length of divisor at decimal. If less than zero, nothing added.
        divplace2& = INSTR(d2dividend$, ".")
        DO UNTIL RIGHT$(d2dividend$, 1) <> "0"
            d2dividend$ = MID$(d2dividend$, 1, LEN(d2dividend$) - 1) ' Strip off trailing zeros
        LOOP
        d2dividend$ = MID$(d2dividend$, 1, INSTR(d2dividend$, ".") - 1) + MID$(d2dividend$, INSTR(d2dividend$, ".") + 1) ' Strip off decimal point.
    ELSE
        d2dividend$ = d2dividend$ + STRING$(divplace&, "0") ' Add any zeros based on the length of dividend at decimal - length of divisor at decimal. If less than zero, nothing added.
        divplace& = 0
    END IF
    DO
        DO
            divremainder& = divremainder& + 1: divremainder$ = divremainder$ + MID$(d2dividend$, divremainder&, 1)
            IF MID$(d2dividend$, divremainder&, 1) = "" THEN
                IF divremainder$ = STRING$(LEN(divremainder$), "0") AND LEN(quotient$) > LEN(d2dividend$) THEN
                    divflag% = -1
                    terminating_decimal% = -1
                    EXIT DO
                END IF
                divcarry& = divcarry& + 1
                IF divcarry& = 1 THEN divplace3& = divremainder& - 1
                IF divcarry& > limit&& + 1 + divbuffer& THEN
                    divflag% = -2: EXIT DO
                END IF
                divremainder$ = divremainder$ + "0" ' No more digits to bring down.
            END IF
            IF LEN(divremainder$) > LEN(d1divisor$) OR LEN(divremainder$) = LEN(d1divisor$) AND divremainder$ >= d1divisor$ THEN EXIT DO
            quotient$ = quotient$ + "0"
        LOOP
        IF divflag% THEN divflag% = 0: EXIT DO

        w1% = VAL(MID$(d1divisor$, 1, 1))
        w2% = VAL(MID$(divremainder$, 1, 1))

        SELECT CASE w1%
            CASE IS > w2%
                w3% = (w2% * 10 + VAL(MID$(divremainder$, 2, 1))) \ w1% + 1
                IF w3% > 9 THEN w3% = 9
            CASE IS = w2%
                IF LEN(divremainder$) > LEN(d1divisor$) THEN w3% = (w2% * 10) \ w1% + 1 ELSE w3% = 2
            CASE IS < w2%
                IF LEN(divremainder$) < LEN(d1divisor$) THEN w3% = (w2% * 10) \ w1% + 1 ELSE w3% = w2% \ w1%
        END SELECT

        FOR div_i% = w3% TO 1 STEP -1
            stringmatha$ = LTRIM$(STR$(div_i%)): stringmathb$ = d1divisor$
            runningtotal$ = sm_mult$(stringmatha$, stringmathb$) ''''GOSUB string_multiply_new ' Gets runningtotal$
            tempcutd$ = divremainder$ ' divremainder$ can be 00 or other leading zero values.
            DO
                IF LEN(tempcutd$) = 1 THEN EXIT DO
                IF LEFT$(tempcutd$, 1) = "0" THEN
                    tempcutd$ = MID$(tempcutd$, 2)
                ELSE
                    EXIT DO
                END IF
            LOOP
            IF LEN(tempcutd$) > LEN(runningtotal$) OR LEN(tempcutd$) = LEN(runningtotal$) AND runningtotal$ <= tempcutd$ THEN EXIT FOR
        NEXT

        quotient$ = quotient$ + LTRIM$(STR$(div_i%))
        stringmatha$ = LTRIM$(STR$(div_i%)): stringmathb$ = d1divisor$
        runningtotal$ = sm_mult$(stringmatha$, stringmathb$) ''''GOSUB string_multiply_new ' Gets runningtotal$
        stringmatha$ = divremainder$: stringmathb$ = runningtotal$
        runningtotal$ = sm_sub$(stringmatha$, stringmathb$) '''''operator$ = "-": GOSUB string_add_subtract_new
        divremainder$ = runningtotal$
    LOOP

    IF divplace& = 0 AND divplace2& = 0 THEN divplace& = divplace3&
    IF divplace2& THEN divplace& = divplace& + divplace2& - 1
    IF quotient$ = "" THEN divplace& = 0 ' dividend is zero.
    IF divplace& OR divplace2& THEN
        quotient$ = MID$(quotient$, 1, divplace&) + "." + MID$(quotient$, divplace& + 1)
        DO UNTIL RIGHT$(quotient$, 1) <> "0"
            quotient$ = MID$(quotient$, 1, LEN(quotient$) - 1) ' Strip off trailing zeros
        LOOP
        IF RIGHT$(quotient$, 1) = "." THEN quotient$ = MID$(quotient$, 1, LEN(quotient$) - 1) ' Strip off abandoned decimal.
    END IF
    DO UNTIL LEFT$(quotient$, 1) <> "0"
        quotient$ = MID$(quotient$, 2) ' Strip off leading zeros
    LOOP
    IF quotient$ = "" THEN quotient$ = "0": divsign% = 0
    stringmathb$ = quotient$: quotient$ = ""

    IF stringmathb$ = "overflow" THEN divsign% = 0: EXIT FUNCTION

    runningtotal$ = stringmathb$: stringmathb$ = ""
    IF divsign% THEN runningtotal$ = "-" + runningtotal$

    IF stringmathround$ <> "" THEN runningtotal$ = runningtotal$ + stringmathround$
    sm_div_old$ = runningtotal$
END FUNCTION

SUB bAdd (s1$, s2$, out$)
    DIM last1%, dp1%, sign1%, last2%, dp2%, sign2%
    DIM last%, d1%, d2%, dpt%, carry%
    DIM i%, n%

    'strip the numbers
    bStripDp s1$, last1%, dp1%, sign1%
    bStripDp s2$, last2%, dp2%, sign2%

    'treat different signs as subtraction and exit
    IF sign1% = negative AND sign2% = positive THEN
        bSub s2$, s1$, out$
        bNeg s1$
        EXIT SUB
    ELSEIF sign1% = positive AND sign2% = negative THEN
        bSub s1$, s2$, out$
        bNeg s2$
        EXIT SUB
    END IF

    'align the decimal points and digit pointers
    last% = bMaxInt%(last1% - dp1%, last2% - dp2%)
    d1% = last% + dp1%
    d2% = last% + dp2%
    dpt% = bMaxInt%(dp1%, dp2%)
    last% = dpt% + last%
    out$ = SPACE$(last%)
    carry% = 0

    'do the addition right to left
    FOR i% = last% TO 1 STEP -1
        IF i% <> dpt% THEN
            n% = carry%
            IF d1% > 0 THEN n% = n% + VAL(MID$(s1$, d1%, 1))
            IF d2% > 0 THEN n% = n% + VAL(MID$(s2$, d2%, 1))
            carry% = n% \ 10
            MID$(out$, i%, 1) = CHR$(asc0 + (n% MOD 10))
        ELSE
            MID$(out$, i%, 1) = dp_tree$
        END IF
        d1% = d1% - 1
        d2% = d2% - 1
    NEXT i%
    IF carry% THEN out$ = one$ + out$

    'clean up
    IF sign1% = negative THEN s1$ = neg$ + s1$: s2$ = neg$ + s2$: out$ = neg$ + out$
    bClean s1$
    bClean s2$
    bClean out$
END SUB

SUB bSub (s1$, s2$, out$)
    DIM last1%, dp1%, sign1%
    DIM last2%, dp2%, sign2%
    DIM last%, d1%, d2%, dpt%, borrow%, swapflag%
    DIM i%, n%

    'strip the numbers
    bStripDp s1$, last1%, dp1%, sign1%
    bStripDp s2$, last2%, dp2%, sign2%

    'treat different signs as addition
    IF sign1% = negative AND sign2% = positive THEN
        bNeg s1$
        bNeg s2$
        bAdd s1$, s2$, out$
        bNeg s2$
        EXIT SUB
    ELSEIF sign1% = positive AND sign2% = negative THEN
        bAdd s1$, s2$, out$
        bNeg s2$
        EXIT SUB
    END IF

    'align the decimal points and digit pointers
    last% = bMaxInt%(last1% - dp1%, last2% - dp2%)
    d1% = last% + dp1%
    d2% = last% + dp2%
    dpt% = bMaxInt%(dp1%, dp2%)
    last% = dpt% + last%
    out$ = SPACE$(last%)
    borrow% = 0

    'always subtract smaller from bigger to avoid complements
    IF bIsMore%(s2$, s1$) THEN
        bSwapString s1$, s2$
        bSwapInt d2%, d1%
        swapflag% = True
    END IF

    'do the subtraction right to left
    FOR i% = last% TO 1 STEP -1
        IF i% <> dpt% THEN
            IF d1% > 0 THEN n% = VAL(MID$(s1$, d1%, 1)) ELSE n% = 0
            IF d2% > 0 THEN n% = n% - VAL(MID$(s2$, d2%, 1))
            n% = n% - borrow%
            IF n% >= 0 THEN borrow% = 0 ELSE borrow% = 1: n% = n% + 10
            MID$(out$, i%, 1) = CHR$(asc0 + n%)
        ELSE
            MID$(out$, i%, 1) = dp_tree$
        END IF
        d1% = d1% - 1
        d2% = d2% - 1
    NEXT i%

    'clean up
    IF sign1% = negative THEN s1$ = neg$ + s1$: s2$ = neg$ + s2$
    IF swapflag% THEN
        bSwapString s1$, s2$
        sign1% = -sign1%
    END IF
    IF sign1% = negative THEN out$ = neg$ + out$
    bClean s1$
    bClean s2$
    bClean out$

END SUB

SUB bSqr (s$, out$)
    DIM dvd$, div$, dig$, newdiv$, t$, z$
    DIM slog%, ssign%, slen%, spt%, olddigits%, n%, m%

    IF bIsNeg%(s$) THEN out$ = errormsg$: EXIT SUB

    'strip to whole number + group digits by 2 left or right of decimal
    bLogGet s$, slog%, ssign%, True
    slen% = LEN(s$)
    IF slog% MOD 2 THEN spt% = 2 ELSE spt% = 1

    'Force at least enough digits to show integer of root
    olddigits% = digits%
    n% = 1 + slog% \ 2
    IF digits% < n% THEN digits% = n%

    'figure first digit and setup loop
    n% = VAL(LEFT$(s$ + "0", spt%))
    m% = INT(SQR(n%))
    out$ = LTRIM$(STR$(m%))
    dvd$ = LTRIM$(STR$(n% - m% * m%))
    spt% = spt% + 1

    DO
        'all done?
        IF (spt% > slen% AND bIsZero%(dvd$)) OR LEN(out$) >= digits% THEN EXIT DO

        'append next 2 digits (or 0s) to dividend
        dvd$ = dvd$ + LEFT$(MID$(s$, spt%, 2) + "00", 2)
        spt% = spt% + 2

        'divisor=twice the root * 10
        z$ = out$
        bAdd out$, z$, div$
        bShift div$, 1

        'estimate divisor, and adjust if too big.  Unit is next digit of root.
        bDivInt dvd$, div$, dig$
        DO
            bAdd div$, dig$, newdiv$
            bMul newdiv$, dig$, t$
            IF NOT bIsMore%(t$, dvd$) THEN EXIT DO
            bInc dig$, -1
        LOOP
        out$ = out$ + dig$

        'form new divisor
        z$ = dvd$
        bSub z$, t$, dvd$

    LOOP

    'clean up
    bLogPut s$, slog%, ssign%
    IF slog% < 0 THEN slog% = slog% - 1
    bLogPut out$, slog% \ 2, ssign%
    digits% = olddigits%

END SUB

SUB bMul (s1$, s2$, out$)
    DIM t$
    DIM slog1%, sign1%, slog2%, sign2%, outdp%, outsign%, outlog%, swapflag%

    'strip multiplier
    t$ = s2$
    bLogGet t$, slog2%, sign2%, True

    'times 0
    IF t$ = zero$ THEN
        out$ = zero$

        'do powers of 10 with shifts
    ELSEIF t$ = one$ THEN
        out$ = s1$
        sign1% = bSign%(out$)
        IF sign1% = negative THEN bAbs out$
        bShift out$, slog2%
        IF sign1% <> sign2% THEN bNeg out$

        'the hard way
    ELSE
        'strip all
        s2$ = t$: t$ = ""
        bLogGet s1$, slog1%, sign1%, True

        'figure decimal point and sign of answer
        outdp% = bLogDp%(s1$, slog1%) + bLogDp%(s2$, slog2%)
        IF sign1% <> sign2% THEN outsign% = negative ELSE outsign% = positive

        'always multiply by the shorter number
        IF LEN(s2$) > LEN(s1$) THEN bSwapString s1$, s2$: swapflag% = True

        'do it
        IF LEN(s2$) <= maxlongdig THEN bMulLong s1$, s2$, out$ ELSE bMulChar s1$, s2$, out$

        'clean up
        outlog% = bLogDp%(out$, outdp%)
        bLogPut out$, outlog%, outsign%
        IF swapflag% THEN bSwapString s1$, s2$
        bLogPut s1$, slog1%, sign1%
        bLogPut s2$, slog2%, sign2%

    END IF

END SUB

SUB bMulChar (s1$, s2$, out$)
    DIM last1%, last2%, last%
    DIM i%, j%, k%, sj%, ej%
    DIM product&

    last1% = LEN(s1$)
    last2% = LEN(s2$)
    last% = last1% + last2%
    out$ = SPACE$(last%)
    product& = 0
    FOR i% = 0 TO last% - 1
        k% = last1% - i%
        sj% = 1 - k%: IF sj% < 0 THEN sj% = 0
        ej% = last1% - k%: IF ej% > last2% - 1 THEN ej% = last2% - 1
        FOR j% = sj% TO ej%
            product& = product& + VAL(MID$(s1$, k% + j%, 1)) * VAL(MID$(s2$, last2% - j%, 1))
        NEXT j%
        MID$(out$, last% - i%, 1) = CHR$(asc0 + CINT(product& MOD 10&))
        product& = product& \ 10&
    NEXT i%
    IF product& THEN out$ = LTRIM$(STR$(product&)) + out$
END SUB

SUB bMulLong (s1$, s2$, out$)
    DIM last1%, i%
    DIM s2val&, product&

    last1% = LEN(s1$)
    s2val& = VAL(s2$)
    out$ = SPACE$(last1%)
    FOR i% = last1% TO 1 STEP -1
        product& = product& + VAL(MID$(s1$, i%, 1)) * s2val&
        MID$(out$, i%, 1) = CHR$(asc0 + CINT(product& MOD 10&))
        product& = product& \ 10&
    NEXT i%
    IF product& THEN out$ = LTRIM$(STR$(product&)) + out$
END SUB

SUB bDivLong (s1$, s2$, quotient$, remainder$)
    DIM rmdr&, dividend&, divisor&
    DIM dig%, i%

    quotient$ = ""
    rmdr& = 0
    divisor& = VAL(s2$)

    FOR i% = 1 TO digits%
        dividend& = rmdr& * 10& + VAL(MID$(s1$, i%, 1))
        dig% = dividend& \ divisor&
        quotient$ = quotient$ + CHR$(asc0 + dig%)
        rmdr& = dividend& - dig% * divisor&
    NEXT i%

    IF LEN(quotient$) = 0 THEN quotient$ = zero$
    remainder$ = LTRIM$(STR$(rmdr&))

END SUB

SUB bDiv (s1$, s2$, out$)
    DIM t$
    DIM slog1%, sign1%, slog2%, sign2%
    DIM outlog%, outsign%, olddigits%

    'strip divisor
    t$ = s2$
    bLogGet t$, slog2%, sign2%, True

    'divide by zero?
    IF t$ = zero$ THEN
        out$ = Error$

        'do powers of 10 with shifts
    ELSEIF t$ = one$ THEN
        out$ = s1$
        sign1% = bSign%(out$)
        IF sign1% = negative THEN bAbs out$
        bShift out$, -slog2%
        IF sign1% <> sign2% THEN bNeg out$

        'the hard way
    ELSE
        'strip all
        s2$ = t$: t$ = ""
        bLogGet s1$, slog1%, sign1%, True

        'figure decimal point and sign of answer
        outlog% = slog1% + bLogDp%(s2$, slog2%)
        IF sign1% <> sign2% THEN outsign% = negative ELSE outsign% = positive

        'bump digits past leading zeros and always show whole quotient
        olddigits% = digits%
        digits% = digits% + LEN(s2$)
        IF digits% < outlog% + 1 THEN digits% = outlog% + 1

        'do it, ignore remainder
        IF LEN(s2$) <= maxlongdig THEN bDivLong s1$, s2$, out$, t$ ELSE bDivChar s1$, s2$, out$, t$

        'clean up
        bLogPut out$, outlog%, outsign%
        bLogPut s1$, slog1%, sign1%
        bLogPut s2$, slog2%, sign2%
        digits% = olddigits%
    END IF

END SUB

SUB bDivChar (s1$, s2$, quotient$, remainder$)
    DIM last1%, last2%, ldvd%, lrem%, dig%, borrow%
    DIM i%, j%, n%
    DIM dvd$

    last1% = LEN(s1$) 'length of the dividend
    last2% = LEN(s2$) 'length of the divisor
    quotient$ = ""
    remainder$ = ""

    FOR i% = 1 TO digits%
        'get next digit of dividend or zero$ if past end
        IF i% <= last1% THEN
            dvd$ = remainder$ + MID$(s1$, i%, 1)
        ELSE
            dvd$ = remainder$ + zero$
        END IF

        'if dividend < divisor then digit%=0 else have to calculate it.
        'do fast compare using string operations. see bComp%()
        bStripZero dvd$
        ldvd% = LEN(dvd$)
        IF (ldvd% < last2%) OR ((ldvd% = last2%) AND (dvd$ < s2$)) THEN
            'divisor is bigger, so digit is 0, easy!
            dig% = 0
            remainder$ = dvd$

        ELSE
            'dividend is bigger, but no more than 9 times bigger.
            'subtract divisor until we get remainder less than divisor.
            'time hog, average is 5 tries through j% loop.  There's a better way.
            FOR dig% = 1 TO 9
                remainder$ = ""
                borrow% = 0
                FOR j% = 0 TO ldvd% - 1
                    n% = last2% - j%
                    IF n% < 1 THEN n% = 0 ELSE n% = VAL(MID$(s2$, n%, 1))
                    n% = VAL(MID$(dvd$, ldvd% - j%, 1)) - n% - borrow%
                    IF n% >= 0 THEN borrow% = 0 ELSE borrow% = 1: n% = n% + 10
                    remainder$ = CHR$(asc0 + n%) + remainder$
                NEXT j%

                'if remainder < divisor then exit
                bStripZero remainder$
                lrem% = LEN(remainder$)
                IF (lrem% < last2%) OR ((lrem% = last2%) AND (remainder$ < s2$)) THEN EXIT FOR

                dvd$ = remainder$
                ldvd% = LEN(dvd$)
            NEXT dig%

        END IF
        quotient$ = quotient$ + CHR$(asc0 + dig%)
    NEXT i%

END SUB

SUB bLogGet (s$, slog%, sign%, zeroflag%)
    DIM dpt%, n%

    IF LEFT$(s$, 1) = neg$ THEN s$ = MID$(s$, 2): sign% = negative ELSE sign% = positive
    bStripZero s$
    dpt% = INSTR(s$, dp_tree$)
    SELECT CASE dpt%
        CASE 0
            slog% = LEN(s$) - 1
        CASE 1
            n% = dpt% + 1
            DO WHILE MID$(s$, n%, 1) = zero$
                n% = n% + 1
            LOOP
            s$ = MID$(s$, n%)
            slog% = dpt% - n%
        CASE ELSE
            s$ = LEFT$(s$, dpt% - 1) + MID$(s$, dpt% + 1)
            slog% = dpt% - 2
    END SELECT

    'remove trailing 0's if zeroflag%
    IF zeroflag% THEN bStripTail s$

END SUB


SUB bLogPut (s$, slog%, sign%)
    DIM last%

    last% = LEN(s$)
    IF LEN(s$) = 0 OR s$ = zero$ THEN
        s$ = zero$
    ELSEIF slog% < 0 THEN
        s$ = dp_tree$ + STRING$(-slog% - 1, zero$) + s$
    ELSEIF slog% > last% - 1 THEN
        s$ = s$ + STRING$(slog% - last% + 1, zero$) + dp_tree$
    ELSE
        s$ = LEFT$(s$, slog% + 1) + dp_tree$ + MID$(s$, slog% + 2)
    END IF
    bClean s$
    IF sign% = negative THEN s$ = neg$ + s$
END SUB

SUB bInt (s$)
    DIM n%

    n% = INSTR(s$, dp_tree$)
    IF n% THEN
        IF n% = 1 THEN s$ = zero$ ELSE s$ = LEFT$(s$, n% - 1)
        IF s$ = neg$ OR LEFT$(s$, 2) = "-." THEN s$ = zero$
    END IF

END SUB

SUB bStr (s$, out$)
    DIM t$
    DIM n%, i%

    n% = INSTR(s$, ".")
    IF n% THEN t$ = MID$(s$, n% + 1) ELSE t$ = RIGHT$(s$, 1)
    out$ = ""
    FOR i% = 1 TO VAL(s$)
        out$ = t$ + out$
    NEXT i%
    IF LEN(out$) = 0 THEN out$ = zero$

END SUB

'Trim leading spaces, add decimal points, eliminate signs.
'Returns last%=length of string, dpt%=decimal place, sign%=-1 or 1.
'Called only by bAdd() and bSub() which needs a final decimal point.
'
SUB bStripDp (s$, last%, dpt%, sign%)
    IF LEFT$(s$, 1) = neg$ THEN s$ = MID$(s$, 2): sign% = negative ELSE sign% = positive
    bStripZero s$
    IF INSTR(s$, dp_tree$) = 0 THEN s$ = s$ + dp_tree$
    IF s$ = dp_tree$ THEN s$ = "0."
    dpt% = INSTR(s$, dp_tree$)
    last% = LEN(s$)
END SUB

'Strip trailing 0s to "." (but leave something)
'
SUB bStripTail (s$)
    DIM n%

    n% = LEN(s$)
    DO WHILE MID$(s$, n%, 1) = zero$
        n% = n% - 1
        IF n% <= 1 THEN EXIT DO
    LOOP
    IF n% THEN IF MID$(s$, n%, 1) = dp_tree$ THEN n% = n% - 1
    s$ = LEFT$(s$, n%)
    IF LEN(s$) = 0 THEN s$ = zero$
END SUB

'Strip leading 0s and final "." (but leave something)
'
SUB bStripZero (s$)
    DIM n%

    n% = 1
    DO WHILE MID$(s$, n%, 1) = zero$
        n% = n% + 1
    LOOP
    IF n% > 1 THEN s$ = MID$(s$, n%)
    IF RIGHT$(s$, 1) = dp_tree$ THEN s$ = LEFT$(s$, LEN(s$) - 1)
    IF LEN(s$) = 0 THEN s$ = zero$
END SUB

SUB bNeg (s$)
    IF LEFT$(s$, 1) = neg$ THEN s$ = MID$(s$, 2) ELSE s$ = neg$ + s$
END SUB

SUB bClean (s$)
    DIM sign%

    IF LEFT$(s$, 1) = neg$ THEN s$ = MID$(s$, 2): sign% = True
    bStripZero s$
    IF INSTR(s$, dp_tree$) THEN bStripTail s$
    IF sign% AND s$ <> zero$ THEN s$ = neg$ + s$

END SUB


SUB bSwapInt (s1%, s2%)
    DIM t%

    t% = s1%
    s1% = s2%
    s2% = t%
END SUB

SUB bSwapString (s1$, s2$)
    DIM t$

    t$ = s1$
    s1$ = s2$
    s2$ = t$
END SUB

SUB bShift (s$, n%)
    DIM slog%, sign%

    bLogGet s$, slog%, sign%, False
    bLogPut s$, slog% + n%, sign%
END SUB

SUB bDivInt (s1$, s2$, out$)
    DIM t$

    bDivIntMod s1$, s2$, out$, t$
END SUB

SUB bDivIntMod (s1$, s2$, quotient$, remainder$)
    DIM slog1%, sign1%, slog2%, sign2%
    DIM olddigits%, outlog%, outsign%

    olddigits% = digits%

    'strip the numbers, set flag false to NOT trim zeros, slower but needed
    bLogGet s2$, slog2%, sign2%, False
    IF s2$ = zero$ THEN quotient$ = Error$: remainder$ = Error$: EXIT SUB
    bLogGet s1$, slog1%, sign1%, False

    'figure decimal point and sign of answer
    outlog% = slog1% + bLogDp%(s2$, slog2%)
    IF sign1% <> sign2% THEN outsign% = negative ELSE outsign% = positive

    'a trick: figure the decimal and only find that many digits
    digits% = outlog% + 1

    'send the work out
    IF LEN(s2$) <= maxlongdig THEN bDivLong s1$, s2$, quotient$, remainder$ ELSE bDivChar s1$, s2$, quotient$, remainder$

    'clean up
    bLogPut s1$, slog1%, sign1%
    bLogPut s2$, slog2%, sign2%
    bClean quotient$
    bClean remainder$
    IF sign1% <> sign2% THEN bNeg quotient$
    digits% = olddigits%

END SUB

SUB bInc (s$, num%)
    DIM dig%, n%, borrow%

    IF num% = 0 THEN EXIT SUB
    dig% = INSTR(s$, dp_tree$)
    IF dig% THEN dig% = dig% - 1 ELSE dig% = LEN(s$)
    n% = num%
    IF n% > 0 THEN 'increment (n>0)
        DO WHILE n%
            IF dig% < 1 THEN
                s$ = LTRIM$(STR$(n%)) + s$
                n% = 0
            ELSE
                n% = n% + VAL(MID$(s$, dig%, 1))
                MID$(s$, dig%, 1) = CHR$(asc0 + (n% MOD 10))
                n% = n% \ 10
                dig% = dig% - 1
            END IF
        LOOP
    ELSE 'decrement (n<0)
        n% = -n%
        DO WHILE n%
            IF dig% < 1 THEN s$ = zero$: EXIT DO
            borrow% = 0
            n% = VAL(MID$(s$, dig%, 1)) - n%
            DO WHILE n% < 0
                n% = n% + 10: borrow% = borrow% + 1
            LOOP
            MID$(s$, dig%, 1) = CHR$(asc0 + n%)
            n% = borrow%
            dig% = dig% - 1
        LOOP
    END IF
    bStripZero s$
END SUB

SUB bAbs (s$)
    IF LEFT$(s$, 1) = neg$ THEN s$ = MID$(s$, 2)
END SUB

SUB bMod (s1$, s2$, out$)
    DIM t$

    bDivIntMod s1$, s2$, t$, out$
END SUB

SUB bModPower (s1$, s2$, s3$, out$)
    'Use variation of "Russian Peasant Method" to figure m=(c^d) mod n.
    'Byte, Jan 83, p.206.
    'test value: (71611947 ^ 63196467) mod 94815109 = 776582

    'm=1
    'do
    '  if d is odd then m=(m*c) mod n
    '  c=(c*c) mod n
    '  d=int(d/2)
    'loop while d>0
    'm is the answer

    DIM c$, d$, z$, w$
    STATIC n$ 'remember modulus for next call

    'positive numbers only, modulus must be >1!  Find mod inverse if s2=-1.
    out$ = errormsg$
    IF LEN(s3$) THEN n$ = s3$
    IF bIsNeg%(s1$) OR bIsNeg%(n$) THEN EXIT SUB
    IF bIsNeg%(s2$) THEN
        IF bIsEqual%(s2$, "-1") THEN bModInv s1$, n$, out$
        EXIT SUB
    END IF

    c$ = s1$
    d$ = s2$
    out$ = one$

    DO
        IF bIsOdd%(d$) THEN
            z$ = out$
            bMul z$, c$, out$
            z$ = out$
            bMod z$, n$, out$
        END IF
        z$ = c$
        w$ = c$
        bMul z$, w$, c$
        z$ = c$
        bMod z$, n$, c$
        z$ = d$
        bDivInt z$, two$, d$
    LOOP UNTIL bIsZero%(d$)

END SUB

SUB bModInv (s1$, s2$, out$)
    DIM g0$, g1$, g2$, v0$, v1$, v2$, y$, t$, z$

    IF NOT bIsRelPrime%(s1$, s2$) THEN out$ = zero$: EXIT SUB

    g0$ = s2$: g1$ = s1$
    v0$ = zero$: v1$ = one$

    DO UNTIL bIsZero%(g1$)
        bDivInt g0$, g1$, y$
        bMul y$, g1$, t$
        bSub g0$, t$, g2$
        bMul y$, v1$, t$
        bSub v0$, t$, v2$
        g0$ = g1$: g1$ = g2$
        v0$ = v1$: v1$ = v2$
    LOOP

    out$ = v0$
    IF bIsNeg%(out$) THEN
        z$ = out$
        bAdd z$, s2$, out$
    END IF
END SUB

SUB bGCD (s1$, s2$, out$)
    DIM div$, dvd$, t$

    'work with copies
    div$ = s1$
    dvd$ = s2$
    IF bIsMore%(div$, dvd$) THEN bSwapString div$, dvd$

    DO UNTIL bIsZero%(div$)
        bMod dvd$, div$, t$
        dvd$ = div$
        div$ = t$
    LOOP
    out$ = dvd$

END SUB


SUB bSqrInt (s$, out$)
    DIM t$
    DIM olddigits%

    IF bIsNeg%(s$) THEN out$ = errormsg$: EXIT SUB
    t$ = s$
    bInt t$

    'a trick: let bSqr() figure the decimal and only find that many digits
    olddigits% = digits%
    digits% = 0
    bSqr t$, out$
    digits% = olddigits%

END SUB

FUNCTION bIsBase% (s$)
    bIsBase% = INSTR(UCASE$(s$), basechr$)
END FUNCTION

'return true if s1 divides s2
'
FUNCTION bIsDiv% (s1$, s2$)
    DIM t$

    bMod s2$, s1$, t$
    bIsDiv% = (t$ = zero$)
END FUNCTION

'return true if s1 = s2
'
FUNCTION bIsEqual% (s1$, s2$)
    bIsEqual% = (s1$ = s2$)
END FUNCTION

'return true if s$ is even, no decimals!
'
FUNCTION bIsEven% (s$)
    bIsEven% = (VAL(RIGHT$(s$, 1)) MOD 2 = 0)
END FUNCTION

'return true if s in an integer (no decimal point).
'
FUNCTION bIsInteger% (s$)
    bIsInteger% = (INSTR(s$, dp_tree$) = 0)
END FUNCTION

'return true if s1 < s2
'
FUNCTION bIsLess% (s1$, s2$)
    bIsLess% = (bComp%(s1$, s2$) = -1)
END FUNCTION

FUNCTION bComp% (s1$, s2$)
    DIM s1flag%, s2flag%, sign1%, sign2%
    DIM dp1%, dp2%, arg%

    'kludge to fix 0<.1
    IF LEFT$(s1$, 1) = dp_tree$ THEN s1$ = zero$ + s1$: s1flag% = True
    IF LEFT$(s2$, 1) = dp_tree$ THEN s2$ = zero$ + s2$: s2flag% = True

    sign1% = (LEFT$(s1$, 1) = neg$)
    sign2% = (LEFT$(s2$, 1) = neg$)
    dp1% = INSTR(s1$, dp_tree$): IF dp1% = 0 THEN dp1% = LEN(s1$) + 1
    dp2% = INSTR(s2$, dp_tree$): IF dp2% = 0 THEN dp2% = LEN(s2$) + 1

    IF sign1% <> sign2% THEN
        IF sign1% THEN arg% = -1 ELSE arg% = 1
    ELSEIF s1$ = s2$ THEN
        arg% = 0
    ELSEIF (dp1% < dp2%) OR ((dp1% = dp2%) AND (s1$ < s2$)) THEN
        arg% = -1
    ELSE
        arg% = 1
    END IF

    IF sign1% AND sign2% THEN arg% = -arg%
    IF s1flag% THEN s1$ = MID$(s1$, 2)
    IF s2flag% THEN s2$ = MID$(s2$, 2)
    bComp% = arg%

END FUNCTION

'return true if s1 > s2
'
FUNCTION bIsMore% (s1$, s2$)
    bIsMore% = (bComp%(s1$, s2$) = 1)
END FUNCTION

'return true if s is negative
'
FUNCTION bIsNeg% (s$)
    bIsNeg% = (LEFT$(s$, 1) = neg$)
END FUNCTION

FUNCTION bIsNotZero% (s$)
    DIM flag%, i%

    flag% = False
    FOR i% = 1 TO LEN(s$)
        IF INSTR("0-. ", MID$(s$, i%, 1)) = False THEN flag% = True: EXIT FOR
    NEXT i%
    bIsNotZero% = flag%
END FUNCTION

'return true if odd
'
FUNCTION bIsOdd% (s$)
    bIsOdd% = (VAL(RIGHT$(s$, 1)) MOD 2 <> 0)
END FUNCTION

'return true if s is prime
'
FUNCTION bIsPrime% (s$)
    bIsPrime% = (bPrmDiv$(s$, False) = s$)
END FUNCTION

's is pseudoprime to base b if (b,s)=1 and b^(s-1)=1 (mod s).  Integers only!
'
FUNCTION bIsPseudoPrime% (s$, bas$)
    DIM t$, smin$
    DIM flag%

    flag% = False
    IF bIsRelPrime%(s$, bas$) THEN
        smin$ = s$: bInc smin$, -1
        bModPower bas$, smin$, s$, t$
        flag% = (t$ = one$)
    END IF
    bIsPseudoPrime% = flag%
END FUNCTION

'return true if s1 and s2 are relatively prime, ie share no factor
'
FUNCTION bIsRelPrime% (s1$, s2$)
    DIM gcd$

    bGCD s1$, s2$, gcd$
    bIsRelPrime% = bIsEqual%(gcd$, one$)
END FUNCTION

'Return true if s$ is zero$ or null, s$ needn't be clean.
'
FUNCTION bIsZero% (s$)
    DIM flag%, i%

    flag% = True
    FOR i% = 1 TO LEN(s$)
        IF INSTR("0-. ", MID$(s$, i%, 1)) = False THEN flag% = False: EXIT FOR
    NEXT i%
    bIsZero% = flag%
END FUNCTION

FUNCTION bSign% (s$)
    IF bIsNeg%(s$) THEN bSign% = negative ELSE bSign% = positive
END FUNCTION

FUNCTION bLogDp% (s$, logdp%)
    bLogDp% = LEN(s$) - 1 - logdp%
END FUNCTION

FUNCTION bPrmDiv$ (s$, dspflag%)
    DIM num$, sfac$, maxfac$, t$
    DIM lfac&, lnum&, lmaxfac&, ldfac&
    DIM i%, cnt%, flag%, dfac%

    num$ = s$
    bInt num$
    bAbs num$
    IF LEN(num$) <= maxlongdig THEN GOSUB bpdLong ELSE GOSUB bpdChar
    EXIT FUNCTION

    bpdChar:
    'try some classic divisibility tests for small factors.
    'Cf Gardner, Unexpected Hanging, p.160.

    'by 2?
    '  If dspflag% Then
    '  frmBncFactor.lblTryNum.Caption = two$
    '  frmBncFactor.lblTryNum.Refresh
    'End If
    IF VAL(RIGHT$(num$, 1)) MOD 2 = 0 THEN bPrmDiv$ = two$: RETURN

    'by 3?
    'IF dspflag% THEN LOCATE , dspflag%: PRINT three$;
    '  If dspflag% Then
    '  frmBncFactor.lblTryNum.Caption = three$
    '  frmBncFactor.lblTryNum.Refresh
    'End If

    lfac& = 0
    FOR i% = 1 TO LEN(num$)
        lfac& = lfac& + ASC(MID$(num$, i%, 1)) - asc0
    NEXT i%
    IF lfac& MOD 3 = 0 THEN bPrmDiv$ = three$: RETURN

    'by 5?
    'IF dspcol% THEN LOCATE , dspcol%: PRINT five$;
    '  If dspflag% Then
    '  frmBncFactor.lblTryNum.Caption = five$
    '  frmBncFactor.lblTryNum.Refresh
    'End If

    IF VAL(RIGHT$(num$, 1)) MOD 5 = 0 THEN bPrmDiv$ = five$: RETURN

    'by 7, 11, or 13?
    'IF dspcol% THEN LOCATE , dspcol%: PRINT "7+";
    '  If dspflag% Then
    '  frmBncFactor.lblTryNum.Caption = "7+"
    '  frmBncFactor.lblTryNum.Refresh
    'End If

    lfac& = 0
    i% = LEN(num$) + 1
    cnt% = 3
    flag% = True
    DO
        i% = i% - 3: IF i% < 1 THEN cnt% = i% + 2: i% = 1
        IF flag% THEN
            lfac& = lfac& + VAL(MID$(num$, i%, cnt%))
        ELSE
            lfac& = lfac& - VAL(MID$(num$, i%, cnt%))
        END IF
        flag% = NOT flag%
    LOOP WHILE i% > 1
    IF lfac& MOD 7 = 0 THEN bPrmDiv$ = "7": RETURN
    IF lfac& MOD 11 = 0 THEN bPrmDiv$ = "11": RETURN
    IF lfac& MOD 13 = 0 THEN bPrmDiv$ = "13": RETURN

    'main loop, increment factor by 2 or 4.
    sfac$ = "17"
    dfac% = 2
    bSqrInt num$, maxfac$

    DO
        'IF dspcol% THEN LOCATE , dspcol%: PRINT sfac$;
        '    If dspflag% Then
        '  frmBncFactor.lblTryNum.Caption = sfac$
        '  frmBncFactor.lblTryNum.Refresh
        'End If

        bMod num$, sfac$, t$
        IF bIsZero%(t$) THEN EXIT DO
        bInc sfac$, dfac%
        dfac% = 6 - dfac%
        IF bIsMore%(sfac$, maxfac$) THEN sfac$ = num$: EXIT DO
        'If INKEY$ = esc$ Then sfac$ = zero$: Exit Do
    LOOP
    bPrmDiv$ = sfac$
    RETURN

    bpdLong:
    lnum& = VAL(num$)
    IF lnum& <= 1 THEN
        lfac& = 1&
    ELSEIF lnum& MOD 2& = 0& THEN
        lfac& = 2&
    ELSEIF lnum& MOD 3& = 0& THEN
        lfac& = 3&
    ELSE
        lmaxfac& = INT(SQR(lnum&))
        lfac& = 5&
        ldfac& = 2&
        DO
            'IF dspcol% THEN LOCATE , dspcol%: PRINT lfac&;
            '      If dspflag% Then
            '  frmBncFactor.lblTryNum.Caption = LTrim$(Str$(lfac&))
            '  frmBncFactor.lblTryNum.Refresh
            'End If

            IF lnum& MOD lfac& = 0& THEN EXIT DO
            lfac& = lfac& + ldfac&
            ldfac& = 6& - ldfac&
            IF lfac& > lmaxfac& THEN lfac& = lnum&: EXIT DO
        LOOP
    END IF
    bPrmDiv$ = LTRIM$(STR$(lfac&))
    RETURN

END FUNCTION

FUNCTION bMaxInt% (n1%, n2%)
    IF n1% >= n2% THEN bMaxInt% = n1% ELSE bMaxInt% = n2%
END FUNCTION

Pete
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RE: Newton had a fun way to approximate general roots... - by Pete - 09-15-2022, 02:43 AM



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