Speed of GMP relative to MPFR for quad precision calculations

[Torbjorn Granlund]

Jerry <lanceboyle at qwest.net> writes:

  BTW, I _am_ correct in thinking that setting the precision to 30
  digits is roughly quad precision, right? I'm still studying the docs
  and so far have found only references to setting precision by bits,
  not digits. I believe I got the "digits" idea from an example.
  
You need to know about logarithms to convert between counts of binary
digits and decimal digits...

  I am seeing a piece of code that takes about two minutes to execute in
  double precision taking about two _hours_ in 30-digit precision. Does
  that sound about right? FWIW, I am using MPFR through the Ada binding.
  
That's way too much.  At least if you're using plain operations (plus,
minus, mul, div).

I bet Ada adds almost all of that overhead.

-- 
Torbjörn