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Re: weird optimization in sin+cos, x86 backend
On 2/3/2012 1:12 PM, Konstantin Vladimirov wrote:
I agree, that this case have no practical value. It was autogenerated
between other thousands of tests and showed really strange results, so
I decided to ask. I thought, this value fits double precision range
and, according to C standard, all double-precision arithmetics must be
avaliable for it.
Yes, indeed and it was available. There was nothing "really strange"
about the results. The only thing strange was your expectations here :-)
Thanks everybody for explanation, I will constrain trig function
arguments, according to "x is separable with x+pi/4" rule. It seems,
everything works inside this range.
Yes, it is a good idea to only generate useful tests when you
are autogenerating, otherwise you will get garbage in garbage out :-)
With best regards, Konstantin
On Fri, Feb 3, 2012 at 7:13 PM, Robert Dewar<firstname.lastname@example.org> wrote:
On 2/3/2012 10:01 AM, Michael Matz wrote:
No normal math library supports such an extreme range, even basic
identities (like cos^2+sin^2=1) aren't retained with such inputs.
I agree: the program is complete nonsense. It would be useful to know
what the intent was.