Is GMP working properly if it compiles gmp functions w/o errors?

Paul Zimmermann Paul.Zimmermann at
Fri Feb 8 17:29:54 CET 2008

       Dear Andre,

> My question is basicly, if this necessarily means that these function work properly? So far, I have only implemented (+, -, *, /) in the algorithms, but the results seem to be not good enough. E.g. switching from mpf_set_default_prec(50) to mpf_set_default_prec(1000) does not change a lot - and thereafter it stays constant for a precision >1000. Theres a lot of exp, log, factorials and binomial coefficients involved too, that is still computed in double precision. Do you think that the gmp library is working and the main round off problems are in these parts, which could be a reason why the basic arithmetic in gmp does not change too much!?!
> If this is the case, could s.o. please give me a hint how to implement exp, log? I couldnt find sth. about this in the documentation.

it is difficult to guess what your problem is without any concrete example,
however the fact that exp, log, ... are computed in double precision surely
does not help. If you want to implement those functions in multiple-precision,
please do. Otherwise, you can use an existing implementation, for example in
Pari/GP, NTL or MPFR.

Paul Zimmermann

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