problem with the 'math' module in 2.5?

[Chris]

Oh, ok that explains it. Is that why my 16-bit calculator gives me 0?
Carsten Haese wrote:
> On 14 Oct 2006 20:33:13 -0700, Chris wrote
> > >>> from math import *
> > >>> sin(0)
> > 0.0
> > >>> sin(pi)
> > 1.2246063538223773e-016
> > >>> sin(2*pi)
> > -2.4492127076447545e-016
> > >>> cos(0)
> > 1.0
> > >>> cos(pi)
> > -1.0
> > >>> cos(2*pi)
> > 1.0
> >
> > The cosine function works fine, but I'm getting weird answers for sine.
> > Is this a bug? Am I doing something wrong?
>
> You're apparently not correctly reading python's answer to sin(pi).
> 1.2246063538223773e-016 is the scientific notation for the number
> 0.00000000000000012246063538223773, which is pretty darn close to zero, the
> result you probably expected.
>
> You're not getting *exactly* zero because you're not passing in *exactly* pi
> but a close approximation of pi.
>
> I'll leave it as an exercise for the reader to explain why cosine seems to
> work fine. Hint: Look at cos(pi/2) and sin(pi/2).
> 
> -Carsten