GCC beaten by ICC in stupid trig test!

[Robert Dewar]

Scott Robert Ladd wrote:


> 
> 
> Mathematical identities provide good tests of numerical accuracy; I have 
> found instances where certain compilers do *not* compute "sin**2+cos**2" 
> as equal to 1, usually due to a poor implementation of sin and cos.

You definitely cannot assume that sin**2+cos**2 = exactly 1.0 throughout
the defined domain of these functions. Expecting this identity is 
similar to thinking that x**y can be computed using log and exp!

> The actual line of code in question was part of a testing spike, and it 
> had no effect on the actual subject of the original post, and was not 
> intended to be part of a production program.

Sure, in fact I suspect the only use of sin**2+cos**2 in real programs
has to do with testing/exploiting the difference between the value of
this computed expression and 1.0. Yes, I know you can posit macros etc,
but I would be surprised if anyone comes up with a real program where
this expression appears in any other context.