On 2005-03-12 02:59:46 +0100, Gabriel Dos Reis wrote: > You probably noticed that in the polynomial expansion, you are using > an integer power -- which everybody agrees on yield 1 at the limit. > > I'm tlaking about 0^0, when you look at the limit of function x^y > -- which is closer to cpow() tgan powi(). Did you miss that?
When one uses the power notation in mathematics, one (almost) never says when the context is a function R x R -> R or R x Z -> R or whatever. The problem is the same in ISO C99 (and probably other languages), without using extensions: when calling cpow(), the compiler doesn't necessarily know if the user was refering to a function R x R -> R or to a function R x Z -> R. That's why returning 1 for cpow((0,0),(0,0)) would be better IMHO, even though this would mean that some errors wouldn't be detected in the case R x R -> R; but anyway, getting a result that is not NaN doesn't mean that it is correct. BTW, couldn't this be controlled by pragmas? -- Vincent Lefèvre <[EMAIL PROTECTED]> - Web: <http://www.vinc17.org/> 100% accessible validated (X)HTML - Blog: <http://www.vinc17.org/blog/> Work: CR INRIA - computer arithmetic / SPACES project at LORIA
