Re: [OT] __builtin_cpow((0,0),(0,0))

[Duncan Sands <baldrick at free dot fr>]

Hi Robert,

> >>Well if you tell me there are people about there implementing cpow
> >>with log and exp, that's enough for me to decide that Ada should
> >>continue to stay away (the Ada RM has accuracy requirements that
> >>would preclude a broken implementation of this kind) :-)
> > 
> > 
> > the reference manual allows for a "relaxed mode", which doesn't have
> > those accuracy requirements.  I guess -ffast-math and the use of
> > builtins would be appropriate in the relaxed mode.  Do you plan to
> > implement such a mode one day?
> > 
> > Just curious.
> > 
> > All the best,
> > 
> > Duncan.
> 
> No plans, but also note that the use of log/exp for ** besides
> being horribly inaccurate, is also inefficient. Fast accurate
> math is achievable, we don't see a need for a relaxed mode.

if the Ada front-end has an efficient, accurate implementation
of x^y, wouldn't it make sense to move it to the back-end
(__builtin_pow) so everyone can benefit?

Ciao,

Duncan.