Speed of GMP relative to MPFR for quad precision calculations

Jerry lanceboyle at qwest.net
Fri Nov 2 00:30:35 CET 2012


I recently started using MPFR in an application where I am certain that quad precision would be adequate. I have been using MPFR with 30 digits precision. But I just now learned that MPFR provides _exactly_ the specified precision and that GMP uses whatever number of machine words is necessary to meet the specified precision. That makes me think that MPFR is slower than GMP floats.

Indeed, MPFR is running more slowly than I hoped. Would GMP's floating point facility run faster in this application (quad precision) than MPFR? I need only multiplies and adds, and conversion back to double precision at the end.


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