D. J. Bernstein
Fast arithmetic
Integer multiplication benchmarks

MPFUN

MPFUN was written by David Bailey. The MPFUN home page is www.nersc.gov/~dhbailey/mpdist/mpdist.html. Sample code using MPFUN:

     cmp+ precision level 1000
     cmp+ scratch space 2000
           program example
     cmp+ multip integer x, y, z
           read (5, *) x
           read (5, *) y
           z = x * y
           write (6, *) z
           stop
           end

I tried computing a product of two integers below 2^98256 with MPFUN f77-ieee version 2001-08-02 on thoth on 2002.02.24. (More precisely: each integer was 16777215^4095, around 2^98280.) MPFUN took about 74 million cycles.

There is also an MPFUN f90-ieee version 2001-08-02. The documentation says that MPFUN was made several times faster at some point; perhaps this applies to f90-ieee and not f77-ieee. Anyway, I have no intention of looking for a Fortran 90 compiler.