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+---- Thread: Precision Math Software (/showthread.php?tid=1600)
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RE: Precision Math Software - dISP - 04-03-2023
Jack, just a couple of kinda dumb questions.
1) What is the "c =" for in the the calculation c = mpfr_log10(y, x, MPFR_RNDN)? "c" does not appear to be a typical variable you are setting a value to. I surmise that the native language for mpfr is C programming and the "c =" has something to do with using mpfr in basic/qb64?
2) While I down loaded the PDF manual for mpfr I still do not quite understand the purpose of the mpfr_set_si statement.
In your first sample program you have c= mpfr_set_si(x, i, MPFR_RNDN) prior to the log10 calc statement above.
I probably need to find a practical user manual versus the GNU mpfr technical library manual I found.
Thx--
RE: Precision Math Software - Jack - 04-03-2023
1: the functions in mpfr return an int as success/fail value
2: mpfr_set_si(x, i, MPFR_RNDN) simply means set x to the signed integer that's in the variable i
RE: Precision Math Software - dISP - 04-04-2023
Ok, I see. Once a variable, say a floating decimal variable for example, is in the mpfr world, is there a function that can send the value of that variable back to the raw program. Such that the value can be assigned to a non mpfr variable?
Basically the opposite transition of this:
d1=.52118
Call mpfr_init2(x, 166)
c = mpfr_set_flt(x, d1, 166)
RE: Precision Math Software - Jack - 04-04-2023
yes, you have
f!=mpfr_get_flt (x, MPFR_RNDN)
d1#=mpfr_get_d (x, MPFR_RNDN)
df##=mpfr_get_ld(x, MPFR_RNDN)
n&=mpfr_get_si (x, MPFR_RNDN)
n~&=mpfr_get_ui (x, MPFR_RNDN)
and if you look in the include you will see that there are counterparts of these
RE: Precision Math Software - dISP - 04-04-2023
Completely awesome. I had looked at the 'get' function but, I didn't quite figure it out and came to the wrong conclusions on it's use.
I think I pretty much see the whole picture for what I need now.
Thanks Jack - you are amazing and have been a great help.