If you want to use huge factorials for practical calculations related to the magnitude of the number, rather than as a demonstration of being able to exactly determine every digit of such a factorial, then a relatively fast way to do such things in Perl is Math::BigApprox.

Computing 2032597! still takes a while because it actually does the 2 million multiplications and, although Math::BigApprox operations are about 10x faster than Math::BigInt operations (even when using GMP, same for bignum) and don't fail for this case, they are still about 20x slower than vanilla Perl math operations here.

% perl -MMath::BigApprox=c -e'$s= time(); $f= !c(203259); print $f, $ +/, time()-$s," seconds\n"' 4.81043e+990637 14 seconds % perl -MMath::BigApprox=c -e'$s= time(); $f= !c(2032597); print $f, $ +/, time()-$s," seconds\n"' 1e+11938984 133 seconds

Not an ideal solution, but perhaps an option you weren't aware of.

- tye        


In reply to Re: Operations with Extremely Large Numbers (BigApprox) by tye
in thread Operations with Extremely Large Numbers by jjw017

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