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Treebeard's String-Math
#1
just for fun I adapted Treebeard's String-Math arithmetic routines +, -, * and / to QB64 https://web.archive.org/web/202002200200...vault.html
Updated to include Sqr, Log, Exp and trig functions
Code: (Select All)
$Console:Only
_Dest _Console

'BIGNUM.BAS v0.n
'Sep-Dec 1996 by Marc Kummel aka Treebeard.
'Contact mkummel@rain.org, http://www.rain.org/~mkummel/
'
' ** site no longer available, use the link below
' https://web.archive.org/web/20200220020034/http://www.rain.org/~mkummel/tbvault.html

'  Conditions:
'-------------

'This program and source code are yours to use and modify as you will, but
'they are offered as freeware with no warranty whatsoever.  Give me credit,
'but do not distribute any changes under my name, or attribute such changes
'to me in any way.  You're on your own!

Const neg$ = "-"
Const negative = -1
Const positive = 1
Const asc0 = 48
Const dp$ = "."
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&
'======================================
Dim n As String
Dim m As String
Dim c As String
digits% = 35
bInit
n = "7." + String$(digits% - 1, "7")
m = "9." + String$(digits% - 1, "9")
c = ""
bAdd (n), (m), c
Print "n + m = "; c
bSub (n), (m), c
Print "n - m = "; c
bMul (n), (m), c
Print "n * m = "; c
bDiv (n), (m), c
Print "n / m = "; c
bSqr "2", c
Print "Sqr(2) = "; c
bLn "2", c
Print "Ln(2) = "; c
bLog "2", "10", c
Print "Log10(2) = "; c
bSin "1", c
Print "Sin(1) = "; c
bCos "1", c
Print "Cos(1) = "; c
bTan "1", c
Print "Tan(1) = "; c
'======================================
' BNCxx.BAS
' BNC math module
' 1997 by Marc Kummel aka Treebeard.
' Contact mkummel@rain.org, http://www.rain.org/~mkummel/

's = |s|
'
Sub bAbs (s$)
    If Left$(s$, 1) = neg$ Then s$ = Mid$(s$, 2)
End Sub

'out = s1 + s2
'
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$, i%, 1) = dp$
        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

'out = arccos(s)
'
Sub bArcCos (s$, out$)
    Dim t$, t2$

    '             pi
    ' Arccos(x) = -- - Arcsin(x)
    '              2

    bPi t$
    t2$ = t$
    bDiv t2$, two$, t$
    bArcSin s$, out$
    If out$ <> Error$ Then bSub t$, (out$), out$

End Sub

'out = arccosh(s)
'
Sub bArcCosh (s$, out$)
    'acosh(x) = Log(x + Sqr(x * x - 1))
    out$ = zero$
End Sub

'out =arccot(s)
'
Sub bArcCot (s$, out$)
    'acot(x) = Atn(x) + pi / 2
    out$ = zero$
End Sub

'out =arccoth(s)
'
Sub bArcCoth (s$, out$)
    'acoth(x) = Log((x + 1) / (x - 1)) / 2
    out$ = zero$
End Sub

'out = arccsc(s)
'
Sub bArcCsc (s$, out$)
    'acsc(x) = Atn(x / Sqr(x * x - 1)) + (Sgn(x) - 1) * pi / 2
    out$ = zero$
End Sub

'out = arccsch(s)
'
Sub bArcCsch (s$, out$)
    'acsch(x) = Log((Sgn(x) * Sqr(x * x + 1) + 1) / x)
    out$ = zero$
End Sub

'out = arcsec(s)
'
Sub bArcSec (s$, out$)
    'asec(x) = Atn(x / Sqr(x * x - 1)) + Sgn(Sgn(x) - 1) * pi / 2
    out$ = zero$
End Sub

'out = arcsech(s)
'
Sub bArcSech (s$, out$)
    'asech(x) = Log(Sqr((-x * x + 1) + 1) / x)
    out$ = zero$
End Sub

'out = arcsin(s)
'
Sub bArcSin (s$, out$)
    Dim t$, t2$

    '                       x
    ' Arcsin(x) = Arctan --------
    '                    û(1-x^2)
    t2$ = s$
    bMul t2$, s$, t$
    bTrimDig t$
    t2$ = t$
    bSub one$, t2$, t$
    If bIsNeg%(t$) Then
        out$ = Error$
    ElseIf bIsZero%(t$) Then
        bPi out$
        t2$ = out$
        bDiv t2$, two$, out$
    Else
        t2$ = t$
        bSqr t2$, t$
        t2$ = t$
        bDiv s$, t2$, t$
        bTrimDig t$
        bArcTan t$, out$
    End If
End Sub

'out = arcsinh(s)
'
Sub bArcSinh (s$, out$)
    'asinh(x) = Log(x + Sqr(x * x + 1))
    out$ = zero$
End Sub

'out = arctan(s)
'
Sub bArcTan (s$, out$)
    Dim t$, tfac$, fac$, d$, z$
    Dim olddigits%, flag%

    olddigits% = digits%
    digits% = digits% + 5
    t$ = s$: bAbs t$
    If bIsMore%(t$, one$) Then GoSub aTan2 Else GoSub aTan1
    digits% = olddigits%
    bTrimDig out$
    Exit Sub

    'both routines are slow when |x|=1!

    'for -1 < x < 1
    '                x^3   x^5   x^7
    'arctan(x) = x - --- + --- - --- + ...
    '                 3     5     7
    aTan1:
    t$ = s$
    z$ = t$
    bMul z$, t$, tfac$
    bTrimDig tfac$
    out$ = t$
    fac$ = three$
    flag% = False

    Do
        z$ = t$
        bMul z$, tfac$, t$
        bTrimDig t$
        bDiv t$, fac$, d$
        bTrimDig d$
        If bIsZero%(d$) Then Exit Do
        If flag% Then
            z$ = out$
            bAdd z$, d$, out$
        Else
            z$ = out$
            bSub z$, d$, out$
        End If
        flag% = Not flag%
        bInc fac$, 2
    Loop

    Return

    'x < -1 or x > 1
    '                  ã   1    1      1      1
    'arctan(x) = (+/-) - - - + ---- - ---- + ---- - ...
    '                  2   x   3x^3   5x^5   7x^7
    aTan2:
    t$ = s$
    z$ = t$
    bMul z$, t$, tfac$
    bTrimDig tfac$
    out$ = t$
    bInv out$
    bNeg out$
    fac$ = three$
    flag% = True
    Do
        z$ = t$
        bMul z$, tfac$, t$
        bTrimDig t$
        bMul t$, fac$, d$
        bTrimDig d$
        bInv d$
        bTrimDig d$
        If bIsZero%(d$) Then Exit Do
        If flag% Then
            z$ = out$
            bAdd z$, d$, out$
        Else
            z$ = out$
            bSub z$, d$, out$
        End If
        flag% = Not flag%
        bInc fac$, 2
    Loop

    digits% = olddigits%
    bPi t$
    z$ = t$
    bDiv z$, two$, t$
    If bIsNeg%(s$) Then bNeg t$
    z$ = out$
    bAdd z$, t$, out$
    Return

End Sub

'out = arctanh(s)
'
Sub bArcTanh (s$, out$)
    'atanh(x) = Log((1 + x) / (1 - x)) / 2
    out$ = zero$
End Sub

'Convert s$ FROM base base1% TO base base2%, including decimals to digits% places.
's$ is modified in place.  No errors for illegal digits, eg 161 base 2 is
'treated as (1*2^2)+(6*2^1)+(1*2^0) even though the "6" is wrong.  Bases
'to 16 are formed with 1..F, but larger bases are formed with digit groups
'separated by commas, eg 6,6,@100=(6*100^1+6*100^0)=606.  Bases ok to 32K!
'Appends "@n" to end of string if base2%<>10, which GetArg() will recognize.
'Slow because of divisions, but the decimals are fun.
'
Sub bBase (s$, base1%, base2%)
    Dim b1$, b2$, whole$, dec$, n$, r$, t$, tn$, dig$, z$
    Dim negflag%, digmask%, groupflag%, dpt%
    Dim i%, j%, last%, nn%

    If base1% < 2 Or base2% < 2 Then s$ = Error$: Exit Sub
    If base1% = base2% Then Exit Sub
    If Left$(s$, 1) = neg$ Then s$ = Mid$(s$, 2): negflag% = True
    b1$ = LTrim$(Str$(base1%))
    b2$ = LTrim$(Str$(base2%))
    digmask% = Len(LTrim$(Str$(base2% - 1)))

    'convert FROM base base1%
    dpt% = InStr(s$, dp$)
    If dpt% = 0 Then dpt% = Len(s$) + 1

    'if base 10, then we're done
    If base1% = 10 Then
        whole$ = Left$(s$, dpt% - 1)
        dec$ = Mid$(s$, dpt%)

    Else
        'else figure whole part
        n$ = Left$(s$, dpt% - 1)
        GoSub bbConvertString
        whole$ = n$

        'figure decimal part
        n$ = Mid$(s$, dpt% + 1)
        If Len(n$) Then
            GoSub bbConvertString
            bPowerInt b1$, LTrim$(Str$(last%)), t$
            bDiv n$, t$, dec$
        End If
    End If

    'convert TO base base2%
    'if base 10, then we're done
    If base2% = 10 Then
        bAdd whole$, dec$, s$

    Else
        s$ = ""

        'figure whole part
        Do
            z$ = whole$
            bDivIntMod z$, b2$, whole$, n$
            nn% = Val(n$)
            GoSub bbGetDigit
            s$ = dig$ + s$
        Loop Until whole$ = zero$

        'figure decimal part
        If Len(dec$) Then
            s$ = s$ + dp$
            r$ = one$
            Do
                z$ = r$
                bMul z$, b2$, r$
                bMul dec$, r$, n$
                bInt n$
                nn% = Val(n$)
                GoSub bbGetDigit
                s$ = s$ + dig$
                z$ = n$
                bDiv z$, r$, n$
                z$ = n$
                bSub dec$, z$, n$
                dec$ = n$
            Loop Until dec$ = zero$ Or Len(s$) > digits%
        End If
    End If

    If Len(s$) = 0 Then s$ = zero$
    If s$ <> zero$ Then
        If base2% <> 10 Then s$ = s$ + " " + basechr$ + b2$
        If negflag% Then s$ = neg$ + s$
    End If
    Exit Sub

    'receive whole number n$ in base base1% and return it in base 10
    bbConvertString:
    tn$ = zero$
    last% = Len(n$)
    groupflag% = (base1% > 16) Or (InStr(n$, basesep$) > 0)
    i% = 1
    Do
        If i% > last% Then Exit Do

        If groupflag% Then
            'digits in groups, eg 6,6,b100 = 6*10^1 + 6*10^0
            j% = InStr(i%, n$, basesep$)
            If j% = 0 Then j% = last%
            nn% = Val(Mid$(n$, i%, j%))
            i% = j% + 1

        Else
            'digits 1 by 1, eg 123 or ABC
            nn% = Asc(Mid$(n$, i%, 1))
            i% = i% + 1
            Select Case nn%
                Case 48 To 57: nn% = nn% - 48
                Case 65 To 90: nn% = nn% - 55
                Case Else: nn% = 0
            End Select
        End If

        'skip illegal digits?
        'IF nn% >= base1% THEN nn% = 0

        t$ = tn$
        bMul t$, b1$, tn$
        bInc tn$, nn%
    Loop
    n$ = tn$
    Return

    'return base base2% digit or group for nn%
    bbGetDigit:
    If base2% > 16 Then
        dig$ = LTrim$(Str$(nn%))
        dig$ = String$(digmask% - Len(dig$), zero$) + dig$ + basesep$
    ElseIf nn% < 10 Then
        dig$ = Chr$(nn% + asc0)
    Else
        dig$ = Chr$(nn% + 55)
    End If
    Return

End Sub

'check if s$ is in some other number base and convert it to base 10.
'
Sub bBase10 (s$)
    Dim numbase%

    bBaseCheck s$, numbase%
    If numbase% Then bBase s$, numbase%, 10
End Sub

'return number and base from a string, or 0 if no base (=base 10).
'eg 100b2 returns s$="100" and numbase%=2
'
Sub bBaseCheck (s$, numbase%)
    Dim i%, n%

    If bIsBase%(s$) Then
        'deal with 6bb16 (=6B hex)
        For i% = Len(s$) To 1 Step -1
            If UCase$(Mid$(s$, i%, 1)) = basechr$ Then n% = i%: Exit For
        Next i%
        numbase% = Val(Mid$(s$, n% + 1))
        s$ = Left$(s$, n% - 1)
    Else
        numbase% = False
    End If
End Sub

'Strip a number to "standard form" with no leading or trailing 0s and no
'final "."  All routines should return all arguments in this form.
'
Sub bClean (s$)
    Dim sign%

    If Left$(s$, 1) = neg$ Then s$ = Mid$(s$, 2): sign% = True
    bStripZero s$
    If InStr(s$, dp$) Then bStripTail s$
    If sign% And s$ <> zero$ Then s$ = neg$ + s$

End Sub

'clean up a number for display so .6 -> 0.6
'
Sub bCleanShow (s$)
    bClean s$
    If Left$(s$, 2) = "-." Then
        s$ = "-0." + Mid$(s$, 3)
    ElseIf Left$(s$, 1) = dp$ Then
        s$ = zero$ + s$
    End If
End Sub

'Compare two numbers using fast string compares.  This can screw up since it
'uses string length, eg it reports "8"<"8." so watch out.  The practice in
'these routines is no leading or trailing 0s and no final "."  See bClean().
'
'Return 1 if s1 > s2
'       0 if s1 = s2
'      -1 if s1 < s2
'
Function bComp% (s1$, s2$)
    Dim s1flag%, s2flag%, sign1%, sign2%
    Dim dp1%, dp2%, arg%

    'kludge to fix 0<.1
    If Left$(s1$, 1) = dp$ Then s1$ = zero$ + s1$: s1flag% = True
    If Left$(s2$, 1) = dp$ Then s2$ = zero$ + s2$: s2flag% = True

    sign1% = (Left$(s1$, 1) = neg$)
    sign2% = (Left$(s2$, 1) = neg$)
    dp1% = InStr(s1$, dp$): If dp1% = 0 Then dp1% = Len(s1$) + 1
    dp2% = InStr(s2$, dp$): If dp2% = 0 Then dp2% = Len(s2$) + 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

'out = cos(x)
'
Sub bCos (s$, out$)
    Dim t$, tfac$, fac$, z$
    Dim nfac&
    Dim olddigits%, flag%

    '             x^2   x^4   x^6
    'cos(x) = 1 - --- + --- - --- + ...
    '              2!    4!    6!

    t$ = s$
    bNormRad t$
    olddigits% = digits%
    digits% = digits% + 5
    z$ = t$
    bMul t$, z$, tfac$
    bTrimDig tfac$
    t$ = one$
    nfac& = 2
    fac$ = two$
    out$ = t$
    flag% = False

    Do
        z$ = t$
        bMul z$, tfac$, t$
        bTrimDig t$
        z$ = t$
        bDiv z$, fac$, t$
        bTrimDig t$
        If bIsZero%(t$) Then Exit Do
        If flag% Then
            z$ = out$
            bAdd z$, t$, out$
        Else
            z$ = out$
            bSub z$, t$, out$
        End If
        flag% = Not flag%
        fac$ = LTrim$(Str$((nfac& + 1&) * (nfac& + 2&)))
        nfac& = nfac& + 2&
    Loop

    digits% = olddigits%
    bTrimDig out$

End Sub

'out = cosh(x)
'
Sub bCosh (s$, out$)
    'cosh(x) = (Exp(x) + Exp(-x)) / 2
    out$ = zero$
End Sub

'out = cot(s)
'
Sub bCot (s$, out$)
    Dim t$, tc$, ts$

    'cot=cos/sin
    t$ = s$
    bNormRad t$
    bSin t$, ts$
    If bIsZero%(ts$) Then
        out$ = Error$
    Else
        bCos t$, tc$
        bDiv tc$, ts$, out$
    End If

End Sub

'out = coth(s)
'
Sub bCoth (s$, out$)
    'coth(x) = (Exp(x) + Exp(-x)) / (Exp(x) - Exp(-x))
    out$ = zero$
End Sub

'out = csc(s)
'
Sub bCsc (s$, out$)
    'csc(s)=1/sin(s)

    bSin s$, out$
    If bIsZero%(out$) Then
        out$ = Error$
    Else
        bInv out$
    End If

End Sub

'out = csch(s)
'
Sub bCsch (s$, out$)
    'csch(x) = 2 / (Exp(x) - Exp(-x))
    out$ = zero$
End Sub

'return decimal part of number (or 0)
'
Sub bDec (s$)
    Dim n%

    n% = InStr(s$, dp$)
    If n% Then s$ = Mid$(s$, n%) Else s$ = zero$
End Sub

'degrees to radians, rad=deg*pi/180
'
Sub bDegToRad (s$)
    Dim t$, z$

    bPi t$
    z$ = t$
    bDiv z$, "180", t$
    z$ = s$
    bMod z$, "360", s$
    z$ = s$
    bMul t$, z$, s$
End Sub

'out = s1 / s2
'
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

'out = s1 / s2 using character algorithm, digit by digit, slow but honest.
's1$ and s2$ must be stripped first, no decimals.
'
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

'out = integer part of s1 / s2
'
Sub bDivInt (s1$, s2$, out$)
    Dim t$

    bDivIntMod s1$, s2$, out$, t$
End Sub

's1 / s2 = integer and remainder (s1 = s2 * q + r)
'bDivInt() and bDivMod() call this.
'
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

'out = s1 / s2 using fast long-integer algorithm. s2$ must be <= 8 digits.
's1$ and s2$ must be stripped first, no decimals.
'
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

'Return an ellipsis... repeat just the decimal or whole string if no decimal.
'Stop at digits% length.  Handy for big test numbers.
'
Sub bDot (s$, out$)

    Dim t$
    Dim n%

    n% = InStr(s$, dp$)
    If n% Then t$ = Mid$(s$, n% + 1) Else t$ = s$
    out$ = s$
    Do
        out$ = out$ + t$
    Loop Until Len(out$) >= digits%
    out$ = Left$(out$, digits%)

End Sub

'out = e^s
'
Sub bExp (s$, out$)
    Dim t$, fac$, z$
    Dim olddigits%, eflag%

    olddigits% = digits%

    'if e^1, see if we already have it.
    If bIsEqual%(s$, one$) Then
        bMemory t$, emem, memget
        If digits% <= Len(t$) - 1 Then out$ = t$: bTrimDig out$: Exit Sub
        eflag% = True
    End If
    digits% = digits% + 5

    'e^x = 1 + x + x^2/2! + x^3/3! + ...

    out$ = one$
    t$ = one$
    fac$ = one$

    Do
        z$ = t$
        bMul z$, s$, t$
        bTrimDig t$
        z$ = t$
        bDiv z$, fac$, t$
        bTrimDig t$
        If bIsZero%(t$) Then Exit Do
        z$ = out$
        bAdd z$, t$, out$
        bInc fac$, 1
    Loop

    digits% = olddigits%
    bTrimDig out$
    If eflag% Then bMemory out$, emem, memput

End Sub

'out = s!
'
Sub bFactorial (s$, out$)
    Dim t$, mul$, z$
    Dim num&, product&
    Dim last%, i%

    bInt s$
    bAbs s$
    If bIsZero%(s$) Then out$ = one$: Exit Sub '0!=1  really!
    If Len(s$) <= maxlongdig Then GoSub bfLong Else GoSub bfChar
    Exit Sub

    bfChar:
    'start the easy way to 99999999! then finish.  This could take weeks!
    t$ = s$
    s$ = String$(maxlongdig, "9")
    GoSub bfLong
    bSwapString s$, t$
    If out$ = abortmsg$ Then Return

    Do Until t$ = s$
        bInc t$, 1
        z$ = out$
        bMul z$, t$, out$
    Loop
    Return

    bfLong:
    'this is the long-integer multiply slightly customized
    out$ = one$
    For num& = 2& To CLng(Val(s$))
        mul$ = out$
        last% = Len(mul$)
        out$ = Space$(last%)
        product& = 0
        For i% = last% To 1 Step -1
            product& = product& + Val(Mid$(mul$, i%, 1)) * num&
            Mid$(out$, i%, 1) = Chr$(asc0 + CInt(product& Mod 10&))
            product& = product& \ 10&
        Next i%
        If product& Then out$ = LTrim$(Str$(product&)) + out$
    Next num&
    Return

End Sub

'out = GCD(s1,s2)
'figure Greatest Common Divisor using Euclid's Algorithm
'Byte, Jan 86, p. 397
'
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

's += num%
'Fast increment s$ by num% for internal use, but not quite primetime.
's$ must be positive (but decimals are ok).  It's ok to use negative num%
'for decrements but if result goes negative it returns "0" with no warning.
'num% must be an integer +-32k.
'
Sub bInc (s$, num%)
    Dim dig%, n%, borrow%

    If num% = 0 Then Exit Sub
    dig% = InStr(s$, dp$)
    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

'Initialize b_routines, set globals, etc
'
Sub bInit ()
    Dim i%

    'a few defaults
    'digits% = defaultdigits
    errormsg$ = "error"
    abortmsg$ = "abort"

    'clear memory
    zstack% = 0
    For i% = 0 To maxmem
        bmem$(i%) = zero$
    Next i%
    For i% = 1 To maxstack
        zmem$(i%) = zero$
    Next i%

    'useful constants
    cname$(pimem) = "pi": bmem$(pimem) = "3.14159265358979323846264338327"
    cname$(pi2mem) = "2pi": bmem$(pi2mem) = "6.28318530717958647692528676654"
    cname$(emem) = "e": bmem$(emem) = "2.71828182845904523536028747135"
    cname$(phimem) = "phi": bmem$(phimem) = "1.61803398874989484820458683436"
    cname$(ln10mem) = "ln(10)": bmem$(ln10mem) = "2.30258509299404568401799145468"
    cname$(ln2mem) = "ln(2)": bmem$(ln2mem) = ".693147180559945309417232121458"

    bncpath$ = "" 'path for files (or current dir if null)
    prmcntfile$ = "BNPRMCNT.DAT" 'prime count table
    '    LoadPrimeTable

End Sub

's = int(s)
'truncate towards 0 like Basic FIX: bInt(-3.3) returns -3.
'
Sub bInt (s$)
    Dim n%

    n% = InStr(s$, dp$)
    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

'return s1\s2 if s2 is divisor of s1, else return 0.
'
Sub bIntDiv (s1$, s2$, out$)
    Dim t$

    bDivIntMod s1$, s2$, out$, t$
    If t$ <> zero$ Then out$ = zero$
End Sub

's = 1/s
'
Sub bInv (s$)
    Dim z$
    z$ = s$
    bDiv one$, z$, s$
End Sub

'return false or the position of the "B" if s$ is in another number base,
'eg 123b5 and abcb16 return 4.
'
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$) = 0)
End Function

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

'out = LCM(s1,s2)
'figure Least Common Multiple using Euclid's Algorithm for GCD.
'LCM (a,b) = (a*b) / GCD(a,b)
'Byte, Jan 86, p. 397
'
Sub bLcm (s1$, s2$, out$)
    Dim product$, gcd$

    bMul s1$, s2$, product$
    bGCD s1$, s2$, gcd$
    bDivInt product$, gcd$, out$

End Sub

'out = ln(s), natural logarithm
'
Sub bLn (s$, out$)
    Dim t$, d$, tfac$, fac$, z$, w$
    Dim ln10flag%, ln2flag%, olddigits%, flag%

    If Not bIsMore%(s$, zero$) Then out$ = Error$: Exit Sub
    If bIsEqual%(s$, "10") Then
        bMemory t$, ln10mem, memget
        If digits% <= Len(t$) - 1 Then out$ = t$: bTrimDig out$: Exit Sub
        ln10flag% = True
    ElseIf bIsEqual%(s$, "2") Then
        bMemory t$, ln2mem, memget
        If digits% <= Len(t$) - 1 Then out$ = t$: bTrimDig out$: Exit Sub
        ln2flag% = True
    End If
    olddigits% = digits%
    digits% = digits% + 5
    If bIsLess%(s$, "1.6") Then GoSub LnSeries2 Else GoSub LnSeries1
    digits% = olddigits%
    bTrimDig out$
    If ln10flag% Then
        bMemory out$, ln10mem, memput
    ElseIf ln2flag% Then
        bMemory out$, ln2mem, memput
    End If
    Exit Sub

    '              x-1   1  x-1      1  x-1
    'ln(x) = 2 * [ --- + - (---)^3 + - (---)^5 + ... ]  {x > 0}
    '              x+1   3  x+1      5  x+1
    'faster for x > 1.6

    LnSeries1:
    t$ = s$: bInc t$, -1
    d$ = s$: bInc d$, 1
    bDiv t$, d$, out$
    t$ = out$
    z$ = t$
    w$ = t$
    bMul z$, w$, tfac$
    bTrimDig tfac$
    fac$ = three$

    Do
        z$ = t$
        bMul z$, tfac$, t$
        bTrimDig t$
        bDiv t$, fac$, d$
        bTrimDig d$
        If bIsZero%(d$) Then Exit Do
        z$ = out$
        bAdd z$, d$, out$
        bInc fac$, 2
    Loop
    z$ = out$
    bMul z$, two$, out$
    Return

    '                1           1
    'ln(x) = (x-1) - - (x-1)^2 + - (x-1)^3 - ...    {2 >= x > 0}
    '                2           3
    'faster for x < 1.6

    LnSeries2:
    bSub s$, one$, t$
    tfac$ = t$
    out$ = t$
    fac$ = two$
    flag% = False

    Do
        z$ = t$
        bMul z$, tfac$, t$
        bTrimDig t$
        bDiv t$, fac$, d$
        bTrimDig d$
        If bIsZero%(d$) Then Exit Do
        If flag% Then
            z$ = out$
            bAdd z$, d$, out$
        Else
            z$ = out$
            bSub z$, d$, out$
        End If
        flag% = Not flag%
        bInc fac$, 1
    Loop
    Return

End Sub

'out = log(s1) base s2, or ln(s1) if s2=0
'
Sub bLog (s1$, s2$, out$)
    Dim t$, z$

    'log(s) base(n) = ln(s) / ln(n)
    If bIsEqual%(s2$, "-1") Then
        bExp s1$, out$
    ElseIf bIsNeg%(s2$) Then
        out$ = Error$
    Else
        bLn s1$, out$
        If Not bIsZero%(s2$) Then
            bLn s2$, t$
            z$ = out$
            bDiv z$, t$, out$
        End If
    End If
End Sub

'Take whole number and log from bLogGet() and return number of decimal
'places in the expanded number; OR take string and number of decimal points
'desired and return the log.  It works both ways.
'
Function bLogDp% (s$, logdp%)
    bLogDp% = Len(s$) - 1 - logdp%
End Function

'Strip s$ to whole number and base 10 integer logarithm and sign.  Decimal
'point is implied after the first digit, and slog% counts places left or
'right.  bLogPut() reverses the process, and bLogDp() gives info on the
'decimals. Tricky, but it works and simplifies dividing and multipling.
'
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$, dp$)
    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

'Restore a number from the integer and log figured in bLogGet(). s$ is taken
'as a number with the decimal after first digit, and decimal is moved slog%
'places left or right, adding 0s as required. Called by bDiv() and bMul().
'
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$ + String$(-slog% - 1, zero$) + s$
    ElseIf slog% > last% - 1 Then
        s$ = s$ + String$(slog% - last% + 1, zero$) + dp$
    Else
        s$ = Left$(s$, slog% + 1) + dp$ + Mid$(s$, slog% + 2)
    End If
    bClean s$
    If sign% = negative Then s$ = neg$ + s$
End Sub

'return the largest of two integers
'
Function bMaxInt% (n1%, n2%)
    If n1% >= n2% Then bMaxInt% = n1% Else bMaxInt% = n2%
End Function

'Put or Get a number string in a cell.  Only 64k in PDS, much less in QB,
'beep for overflow.
'
Sub bMemory (s$, memcell%, memop%)
    Dim i%

    'in range?
    If memcell% < 0 Or memcell% > maxmem Then Exit Sub

    Select Case memop%
        Case memget: s$ = bmem$(memcell%)
        Case memput
            'check for enough memory?
            bmem$(memcell%) = s$
        Case memclr: For i% = 0 To 9: bmem$(i%) = "": Next i%
    End Select

End Sub

'Perform Miller test for a number and base, return true if s may be prime.
'  Schneier, Applied Cryptography, p.260
'  Robbins, Beginning Number Theory, p.262
'
Function bMillerTest% (s$, bas$)
    Dim t$, z$, rmd$, w$, y$
    Dim j%, flag%

    Static lasts$, smin$, m$, k%
    If bIsEven%(s$) Then bMillerTest% = False: Exit Function

    'figure {k,m} so s = 2^k * m + 1.  Save results for next call.
    If s$ <> lasts$ Then
        smin$ = s$
        bInc smin$, -1
        m$ = smin$
        k% = 0
        Do
            t$ = m$
            bDivIntMod t$, two$, m$, rmd$
            If rmd$ = zero$ Then k% = k% + 1 Else m$ = t$: Exit Do
        Loop
    End If

    bModPower bas$, m$, s$, z$
    If z$ = one$ Or z$ = smin$ Then
        flag% = True
    Else
        flag% = False
        For j% = 1 To k% - 1
            w$ = z$
            y$ = z$
            bMul w$, y$, z$
            w$ = z$
            bMod w$, s$, z$
            If z$ = smin$ Then flag% = True: Exit For
        Next j%
    End If
    bMillerTest% = flag%

End Function

'out = s1 mod s2
'remainder after division, works for non-integers, but doesn't mean much.
'
Sub bMod (s1$, s2$, out$)
    Dim t$

    bDivIntMod s1$, s2$, t$, out$
End Sub

'out = s1^-1 (mod s2)
'Find inverse mod a number with Extended Euclid Algorithm.
'Given a and n, find x such that a*x = 1 (mod n).
'Answer exists only if a and n are relatively prime, else return 0.
'
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

'out = (s1 ^ s2) mod s3
'
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

'out = s1 * s2
'
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

'out = s1 * s2 using character algorithm, slow but honest.  Whole numbers
'only.  Inner loop is optimized and hard to understand, but it works.
'
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

'out = s1 * s2 using fast long-integer algorithm. s2$ must be <= 8 digits.
's1$ and s2$ must be stripped first, whole numbers only.
'
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

'out = nCr, s1 things taken s2 at a time, order doesn't matter
'
Sub bnCr (s1$, s2$, out$)
    '         n!      nPr
    'nCr = -------- = ---
    '      r!(n-r)!    r!

    'nCr = nCn-r, so pick the smaller
    Dim r$, t$, z$

    bSub s1$, s2$, r$
    If bIsMore%(r$, s2$) Then r$ = s2$

    bnPr s1$, r$, t$
    If t$ = errormsg$ Then Exit Sub
    z$ = r$
    bFactorial z$, r$
    bDivInt t$, r$, out$

End Sub

's = -s
'
Sub bNeg (s$)
    If Left$(s$, 1) = neg$ Then s$ = Mid$(s$, 2) Else s$ = neg$ + s$
End Sub

'Normalize s1 to range of +-{s2}
'
Sub bNorm (s1$, s2$)
    Dim t$
    Dim dpt%

    t$ = s1$
    bAbs t$
    If Not bIsLess%(t$, s2$) Then
        bDiv s1$, s2$, t$
        dpt% = InStr(t$, dp$)
        If dpt% = 0 Then
            s1$ = zero$
        Else
            bMul s2$, Mid$(t$, dpt%), s1$
            bTrimDig s1$
            If bIsNeg%(t$) Then bNeg s1$
        End If
    End If
End Sub

'Normalize an angle in radians to +-2pi
'
Sub bNormRad (s$)
    Dim pi2$

    bPi2 pi2$
    bNorm s$, pi2$
End Sub

'out = nPr, s1 things taken s2 at a time, order matters
'
Sub bnPr (s1$, s2$, out$)
    '        n!
    'nPr = ------ = (n)*(n-1)*...*(n-r+1)
    '      (n-r)!

    Dim t$, z$

    bAbs s1$
    bAbs s2$
    If bIsMore%(s2$, s1$) Then out$ = errormsg$: Exit Sub
    If bIsZero%(s2$) Then out$ = one$: Exit Sub
    bSub s1$, s2$, out$
    bInc out$, 1
    t$ = out$

    Do Until t$ = s1$
        bInc t$, 1
        z$ = out$
        bMul t$, z$, out$
    Loop

End Sub

'out = phi (Golden Ratio)
'
Sub bPhi (out$)
    Dim t$
    Dim olddigits%

    olddigits% = digits%

    'see if it's already in memory
    bMemory t$, phimem, memget
    If digits% <= Len(t$) - 1 Then
        out$ = t$
        bTrimDig out$
        Exit Sub
    End If

    'else calculate it.  Need to write this.
    out$ = t$

End Sub

'pi with Machin's formula: pi= 16 arctan(1/5) - 4 arctan(1/239)
'
Sub bPi (out$)
    Dim d$, k$, t$, tfac$, atan$, atan5$, atan239$, z$
    Dim olddigits%, flag%

    olddigits% = digits%

    'see if it's already in memory
    bMemory t$, pimem, memget
    If digits% <= Len(t$) - 1 Then out$ = t$: bTrimDig out$: Exit Sub

    'figure a bit more and truncate to get last place right
    digits% = digits% + 5

    t$ = five$: GoSub bpArctan: atan5$ = atan$
    t$ = "239": GoSub bpArctan: atan239$ = atan$
    bMul four$, atan5$, t$
    bSub t$, atan239$, out$

    digits% = olddigits%
    bTrimDig out$
    bMemory out$, pimem, memput

    Exit Sub

    'Machin's series    1     1       1
    ' 4*arctan(1/n) = { - - ----- + ----- - ... }
    '                   n   3*n^3   5*n^5
    bpArctan:
    z$ = t$
    bMul z$, t$, tfac$
    z$ = t$
    bMul z$, four$, t$
    atan$ = zero$
    k$ = one$
    flag% = True

    Do
        z$ = t$
        bDiv z$, tfac$, t$
        bDiv t$, k$, d$
        bTrimDig d$
        If bIsZero%(d$) Then Exit Do
        If flag% Then
            z$ = atan$
            bAdd z$, d$, atan$
        Else
            z$ = atan$
            bSub z$, d$, atan$
        End If
        flag% = Not flag%
        bInc k$, 2
    Loop
    Return

End Sub

'return s=2*pi, from memory if possible
'
Sub bPi2 (s$)
    Dim z$
    bMemory s$, pi2mem, memget
    If digits% <= Len(s$) - 1 Then
        bTrimDig s$
    Else
        bPi s$
        z$ = s$
        bMul z$, two$, s$
        bMemory s$, pi2mem, memput
    End If
End Sub

'out = s1 ^ s2, for real s2
'
Sub bPower (s1$, s2$, out$)
    Dim z$
    Dim invflag%

    If bIsInteger%(s2$) Then
        bPowerInt s1$, s2$, out$
    Else
        If bIsNeg%(s2$) Then bNeg s2$: invflag% = True
        bLn s1$, out$
        z$ = out$
        bMul z$, s2$, out$
        z$ = out$
        bExp z$, out$
        If invflag% Then bNeg s2$: bInv out$
    End If
End Sub

'out = s1 ^ s2, for integer s2 only!  (It truncates s2)
'Uses variation of "Russian Peasant Method".
'
Sub bPowerInt (s1$, s2$, out$)
    Dim c$, d$, z$, w$
    Dim invflag%

    bInt s2$
    If bIsZero%(s2$) Then out$ = one$: Exit Sub
    If bIsNeg%(s2$) Then bNeg s2$: invflag% = True

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

    Do
        If bIsOdd%(d$) Then
            z$ = out$
            bMul z$, c$, out$
        End If
        z$ = c$
        w$ = c$
        bMul z$, w$, c$
        z$ = d$
        bDivInt z$, two$, d$
    Loop Until bIsZero%(d$)

    If invflag% Then
        bNeg s2$
        z$ = out$
        bDiv one$, z$, out$
    End If
End Sub

'If pflag% then count primes to s and return count else return s_th prime.
'If dspcol% then show progress on current line starting with that column.
'Will go forever if pflag% and s not prime.
'
Function bPrmCount$ (s$, dspcol%, pflag%)
    Dim cnt$, num$
    Dim n&
    Dim i%, dinc%

    'deal with exceptions up front
    Select Case s$
        Case "0": cnt$ = zero$: num$ = zero$
        Case "1": cnt$ = zero$: num$ = two$
        Case "2": cnt$ = one$: num$ = three$
        Case "3": cnt$ = two$: num$ = five$

        Case Else
            'if no prime table then start from scratch else cue into table
            If maxprmcnt% = 0 Then
                i% = 0

                'pflag% true: s$ is prime, count to it and return count
            ElseIf pflag% Then
                If bIsMore%(s$, LTrim$(Str$(prmcnt&(maxprmcnt%)))) Then
                    i% = maxprmcnt%
                Else
                    n& = Val(s$)
                    For i% = 1 To maxprmcnt%
                        If prmcnt&(i%) > n& Then Exit For
                    Next i%
                    i% = i% - 1
                End If

                'pflag% false: s$ is the count, return that prime
            Else
                If bIsMore%(s$, LTrim$(Str$(maxprmcnt% * 1000&))) Then
                    i% = maxprmcnt%
                Else
                    i% = Val(s$) \ 1000
                End If
            End If

            'get start values
            If i% = 0 Then
                num$ = five$: cnt$ = three$
            Else
                num$ = LTrim$(Str$(prmcnt&(i%)))
                cnt$ = LTrim$(Str$(i% * 1000&))
            End If
            If Val(num$) Mod 6 = 1 Then dinc% = 4 Else dinc% = 2

            'finally to work
            Do
                If bIsPrime%(num$) Then
                    'IF dspcol% AND (RIGHT$(cnt$, 2) = "00") THEN PRINT "."; : IF POS(0) = 75 THEN LOCATE , dspcol%: PRINT TAB(80); : LOCATE , dspcol%
                    If pflag% Then
                        If num$ = s$ Then Exit Do
                    Else
                        If cnt$ = s$ Then Exit Do
                    End If
                    bInc cnt$, 1
                End If
                bInc num$, dinc%
                dinc% = 6 - dinc%
            Loop
    End Select
    If pflag% Then bPrmCount$ = cnt$ Else bPrmCount$ = num$

End Function

'Return smallest prime divisor or s$ if prime, no size limit, but slows
'down when s$>8 digits.  This is strictly brute force and slow.  Press <esc>
'to abort and it returns 0.  If dspflag% then print (most) factors in
'lblTryNum of Factor frame, an inelegant kludge used by Factor().  A speed
'hit, but fun to watch.
'
Function bPrmDiv$ (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

'Do Rabin-Miller Prime test times% times.  If true, then probability that
's is composite is < .25^times%.  Of course s$ is an odd integer.
'If dspcol% then show progress on current line starting with that column.
'
Function bPrmTest% (s$, times%, dspflag%)
    Dim n$
    Dim i%, flag%

    If bIsEven%(s$) Then bPrmTest% = False: Exit Function
    flag% = True
    For i% = 2 To times% + 1
        'If dspflag% Then Print ".";
        n$ = LTrim$(Str$(i%))
        If bIsRelPrime%(s$, n$) Then
            flag% = bMillerTest%(s$, n$)
        Else
            flag% = False
        End If
        If Not flag% Then Exit For
    Next i%
    bPrmTest% = flag%
End Function

'radians to degrees, deg=rad*180/pi
'
Sub bRadToDeg (s$)
    Dim t$, z$

    bNormRad s$
    bPi t$
    z$ = t$
    bDiv "180", z$, t$
    z$ = s$
    bMul t$, z$, s$
    bTrimDig s$
End Sub

'Return a random number.  Expects an argument of form m.n:
'  m.n  returns m digits+decimal+n digits
'  m    returns m digits
'  m.   m digits with random decimal point
'<null> use last mask
'
Sub bRand (s$, out$)
    Static randmask$
    Dim t$
    Dim n%

    t$ = s$
    If Len(t$) = 0 Then
        If Len(randmask$) = 0 Then randmask$ = "5"
        t$ = randmask$
    End If

    randmask$ = t$
    n% = InStr(t$, dp$)
    If n% = 0 Then
        'R3 -> abc
        out$ = bRnd$(Val(t$))
    ElseIf n% = 1 Then
        'R.3 -> .abc
        out$ = dp$ + bRnd$(Val(Mid$(t$, 2)))
    ElseIf n% = Len(t$) Then
        'R3. -> abc with random dp
        out$ = bRnd$(Val(t$) + 1)
        Mid$(out$, Int(1 + Rnd * Len(out$)), 1) = dp$
    Else
        'R3.2 -> abc.ef
        out$ = bRnd$(Val(Mid$(t$, 1, n% - 1))) + dp$ + bRnd$(Val(Mid$(t$, n% + 1)))
    End If

End Sub

'Return a random number string of places% digits.
'
Function bRnd$ (places%)
    Dim t$
    Dim i%

    If places% = 0 Then
        bRnd$ = zero$
    Else
        t$ = Space$(places%)
        Mid$(t$, 1, 1) = Chr$(asc0 + Int(Rnd * 9) + 1)
        For i% = 2 To places%
            Mid$(t$, i%, 1) = Chr$(asc0 + Int(Rnd * 10))
        Next i%
        bRnd$ = t$
    End If
End Function

'Return a random number < max$, to digits places.
'
Sub bRndNum (max$, out$)

    bMul LTrim$(Str$(Rnd)), max$, out$

End Sub

'out = s2 root of s1, (or s1 ^ 1/s2)
'
Sub bRoot (s1$, s2$, out$)
    Dim t$, x$, root$, mroot$, r$, newx$, z$
    Dim negflag%, invflag%

    'easy 0 values
    If bIsZero%(s2$) Then out$ = one$: Exit Sub
    If bIsZero%(s1$) Then out$ = zero$: Exit Sub

    'use logs for non-integer roots
    If Not bIsInteger%(s2$) Then
        t$ = s2$: bInv t$
        bPower s1$, t$, out$
        Exit Sub
    End If

    x$ = s1$
    root$ = s2$
    If bIsNeg%(x$) Then If bIsEven%(root$) Then out$ = errormsg$: Exit Sub Else bNeg x$: negflag% = True
    If bIsNeg%(root$) Then bNeg root$: invflag% = True
    If root$ = two$ Then bSqr x$, out$ Else GoSub brRoot
    If invflag% Then bInv out$
    If negflag% Then bNeg out$

    Exit Sub

    'Newton-Raphson method for any integer root
    brRoot:
    mroot$ = root$
    bInc mroot$, -1

    Do
        'newx = [x*(n-1) + s/x^(n-1)] / (n-1)
        bMul x$, mroot$, r$
        bPowerInt x$, mroot$, t$
        bTrimDig t$
        z$ = t$
        bDiv s1$, z$, t$
        bTrimDig t$
        z$ = t$
        bAdd r$, z$, t$
        z$ = t$
        bDiv z$, root$, newx$

        'a bug, these are never equal
        'bTrimDig x$
        'bTrimDig newx$
        'IF x$ = newx$ THEN EXIT DO

        If Left$(x$, digits% - 1) = Left$(newx$, digits% - 1) Then Exit Do
        x$ = newx$
        bTrimDig x$
    Loop

    out$ = newx$

    Return

End Sub

'Take a string in "scientific notation" and expand it.
'Recognize both 66.6e2 AND 66.6d2 as 6660 to accommadate QB.
'                   ^          ^
'
Sub bSci (s$)
    Dim n%, xp%, sign%

    s$ = UCase$(LTrim$(s$))
    n% = InStr(s$, "E")
    If n% = 0 Then n% = InStr(s$, "D") 'because double# use "D" not "E"
    If n% Then
        xp% = Val(Mid$(s$, n% + 1))
        s$ = Left$(s$, n% - 1)
        bLogGet s$, n%, sign%, True
        bLogPut s$, n% + xp%, sign%
    End If
End Sub

'out = sec(x)
'
Sub bSec (s$, out$)
    'sec(x)=1/cos(x)

    bCos s$, out$
    If bIsZero%(out$) Then
        out$ = Error$
    Else
        bInv out$
    End If
End Sub

'out = sech(s)
'
Sub bSech (s$, out$)
    'sech(x) = 2 / (Exp(x) + Exp(-x))
    out$ = zero$
End Sub

'Set digits% to dig% (or return value if 0).
'
Sub bSetDigits (dig%)
    If dig% = False Then dig% = digits% Else digits% = dig%
End Sub

'shift decimal n% digits (minus=left), i.e multiply/divide by 10.
'
Sub bShift (s$, n%)
    Dim slog%, sign%

    bLogGet s$, slog%, sign%, False
    bLogPut s$, slog% + n%, sign%
End Sub

'return sign of number (-1 or +1)
'
Function bSign% (s$)
    If bIsNeg%(s$) Then bSign% = negative Else bSign% = positive
End Function

'out = sin(x)
'
Sub bSin (s$, out$)
    Dim t$, tfac$, fac$, z$
    Dim nfac&
    Dim olddigits%, flag%

    '             x^3   x^5   x^7
    'sin(x) = x - --- + --- - --- + ...
    '              3!    5!    7!

    t$ = s$
    bNormRad t$
    olddigits% = digits%
    digits% = digits% + 5
    z$ = t$
    bMul t$, z$, tfac$
    bTrimDig tfac$
    nfac& = 3
    fac$ = "6"
    out$ = t$
    flag% = False

    Do
        z$ = t$
        bMul z$, tfac$, t$
        bTrimDig t$
        z$ = t$
        bDiv z$, fac$, t$
        bTrimDig t$
        If bIsZero%(t$) Then Exit Do
        If flag% Then
            z$ = out$
            bAdd z$, t$, out$
        Else
            z$ = out$
            bSub z$, t$, out$
        End If
        flag% = Not flag%
        fac$ = LTrim$(Str$((nfac& + 1&) * (nfac& + 2&)))
        nfac& = nfac& + 2&
    Loop

    digits% = olddigits%
    bTrimDig out$

End Sub

'out = sinh(x)  hyperbolic sine
'
Sub bSinh (s$, out$)
    'sinh(x) = (Exp(x) - Exp(-x)) / 2
    out$ = zero$
End Sub

'out = SQR(s) using the old hand method
'I learned this in high school, but I still don't understand it. It's fast.
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

'out = INT(SQR(s)), largest integer n such that n^2 <= s
'
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

'Return a number string.  str(4.31) returns 4 "31"s, i.e. 31313131.
'Handy for big test numbers.
'
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$, dp$) = 0 Then s$ = s$ + dp$
    If s$ = dp$ Then s$ = "0."
    dpt% = InStr(s$, dp$)
    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$ 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$ Then s$ = Left$(s$, Len(s$) - 1)
    If Len(s$) = 0 Then s$ = zero$
End Sub

'out = s1 - s2
'
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$, i%, 1) = dp$
        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 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

'out = tan(s)
'
Sub bTan (s$, out$)
    Dim t$, tc$, ts$

    'tan=sin/cos
    t$ = s$
    bNormRad t$
    bCos t$, tc$
    If bIsZero%(tc$) Then
        out$ = Error$
    Else
        bSin t$, ts$
        bDiv ts$, tc$, out$
    End If
End Sub

Sub bTanh (s$, out$)
    'tanh(x) = (Exp(x) - Exp(-x)) / (Exp(x) + Exp(-x))
    out$ = zero$
End Sub

'Truncate s$ to digits% places
'
Sub bTrimDig (s$)
    s$ = Left$(s$, digits% + 1)
End Sub

'Try to load table of prime counts, 66th item is the 66000th prime.
'Should be in current dircetory, but check path if not.
'
'Sub LoadPrimeTable ()
'    Dim file$, path$, in$
'    Dim i%, n%, m%, flag%, filenum%

'    file$ = prmcntfile$
'    filenum% = FreeFile
'    maxprmcnt% = False

''    if table not in current dir, then check path
'  If Len(Dir$(file$)) = 0 Then
'    path$ = Environ$("PATH")
'    flag% = True
'    n% = 1
'    Do While n% < Len(path$)
'      m% = InStr(n%, path$, ";")
'      If m% = 0 Then m% = Len(path$) + 1
'      file$ = Mid$(path$, n%, m% - n%)
'      If Right$(file$, 1) <> "\" Then file$ = file$ + "\"
'      file$ = file$ + prmcntfile$
'      If Len(Dir$(file$)) Then
'        bncpath$ = Mid$(path$, n%, m% - n%) + "\"
'        flag% = False
'        Exit Do
'      End If
'      n% = m% + 1
'    Loop
'    If flag% Then Exit Sub
'  End If

''  found it, check for signature and load data
'  Open file$ For Input As #filenum%
'  Line Input #filenum%, in$
'  If UCase$(Left$(in$, 7)) = "'BIGNUM" Then
'    Do
'      Line Input #filenum%, in$
'    Loop While Left$(in$, 1) = "'"
'    maxprmcnt% = Val(in$)
'    ReDim prmcnt&(1 To maxprmcnt%)
'    For i% = 1 To maxprmcnt%
'      Input #filenum%, prmcnt&(i%)
'    Next i%
'  End If
'  Close #filenum%

'End Sub

'PUT or GET a number from the stack, or beep
'
Sub WorkStack (s$, memop%)
    Dim i%

    Select Case memop%
        Case memget
            If zstack% Then
                s$ = zmem$(zstack%)
                zstack% = zstack% - 1
            Else
                s$ = zero$ 'stack underflow
            End If
        Case memput
            If (zstack% < maxstack) Then
                zstack% = zstack% + 1
                zmem$(zstack%) = s$
            Else
                'stack overflow
            End If
        Case memclr
            zstack% = False
            For i% = 1 To maxstack: zmem$(i%) = zero$: Next i%
    End Select
End Sub
Reply


Messages In This Thread
Treebeard's String-Math - by Jack - 07-27-2022, 11:52 PM
RE: Treebeard's String-Math - by Pete - 07-28-2022, 02:00 AM
RE: Treebeard's String-Math - by Jack - 07-28-2022, 02:12 AM
RE: Treebeard's String-Math - by Pete - 07-28-2022, 06:17 AM
RE: Treebeard's String-Math - by Jack - 07-28-2022, 10:43 AM
RE: Treebeard's String-Math - by James D Jarvis - 07-28-2022, 03:09 PM
RE: Treebeard's String-Math - by Pete - 07-28-2022, 04:02 PM
RE: Treebeard's String-Math - by James D Jarvis - 07-28-2022, 05:23 PM
RE: Treebeard's String-Math - by Pete - 07-28-2022, 04:55 PM
RE: Treebeard's String-Math - by Kernelpanic - 07-29-2022, 07:06 PM
RE: Treebeard's String-Math - by Jack - 07-29-2022, 08:45 PM
RE: Treebeard's String-Math - by Kernelpanic - 07-29-2022, 09:13 PM
RE: Treebeard's String-Math - by Jack - 07-29-2022, 09:36 PM
RE: Treebeard's String-Math - by Jack - 07-29-2022, 10:33 PM
RE: Treebeard's String-Math - by Pete - 07-29-2022, 11:18 PM
RE: Treebeard's String-Math - by Jack - 07-30-2022, 12:13 AM
RE: Treebeard's String-Math - by Pete - 07-30-2022, 12:30 AM
RE: Treebeard's String-Math - by Jack - 07-30-2022, 12:37 AM
RE: Treebeard's String-Math - by Pete - 07-30-2022, 12:56 AM
RE: Treebeard's String-Math - by Jack - 07-30-2022, 01:05 AM
RE: Treebeard's String-Math - by Pete - 07-30-2022, 02:44 AM
RE: Treebeard's String-Math - by Jack - 07-31-2022, 12:34 PM
RE: Treebeard's String-Math - by bplus - 07-31-2022, 03:03 PM
RE: Treebeard's String-Math - by Jack - 07-31-2022, 04:41 PM
RE: Treebeard's String-Math - by Jack - 08-08-2022, 06:12 PM
RE: Treebeard's String-Math - by bplus - 08-08-2022, 07:23 PM
RE: Treebeard's String-Math - by Jack - 08-08-2022, 09:04 PM



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