mpn_sqrtrem{1,2}

Torbjörn Granlund tg at gmplib.org
Thu Mar 16 13:45:58 UTC 2017


nisse at lysator.liu.se (Niels Möller) writes:

  I think the "long double" type means an 80-bit floating point format
  which was implemented in the original 80387 floating point coprocessor.
  And which isn't supported by the later x86 SIMD instructions (and not
  supported at all on on non-x86 platforms, as far as I'm aware).
  
It is presumably the same as plain double almost everywhere.

We should probably not rely on FP arithmetic in GMP's generic code as it
is not predicatble enough.  Even if we do it just for IEEE 754, we can
not control the rounding mode.  That means that e.g., sqrt(2)^2 will be
greater that 2 sometimes, less than 2 sometimes.

-- 
Torbjörn
Please encrypt, key id 0xC8601622


More information about the gmp-devel mailing list