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From: tony@joshua.math.ucla.edu
Newsgroups: comp.lang.c
Subject: Question regarding pow() function
Message-ID: <400@sunset.MATH.UCLA.EDU>
Date: 1 Feb 89 01:28:18 GMT
Sender: news@MATH.UCLA.EDU
Reply-To: tony@MATH.UCLA.EDU ()
Distribution: na
Organization: UCLA Mathematics Department
Lines: 38

I am having a problem using the pow() function in Micrsoft C and
I was wondering if someone out there can point out what I am doing
wrong.

I'm trying to use the pow () function to raise negative one (-1)
to the power n, i.e. flip the sign back and forth.

What I'm doing is something like:

#include <math.h>
void foo () 
{
    int n ;

    for (n = 0 ; n < 10 ; n++)
        printf ("%lf",pow (-1,n)) ;

}

I am getting a "DOMAIN" error for each pow() call when I do this.  

According to my library guide, the pow function is defined as follows:

        double pow (x,y)
        double x ;
        double y ;

        ...If x is negative and y is not an integer, the function 
        prints a DOMAIN error message to stderr, sets errono to EDOM, 
        and returns 0...

My int n variable is being cast into a double, hence this error.
Can someone tell me how I can get around this?

(I know I can use if statements to see if the sign should be - or +
but I'd rather use the pow() function. Its more elegant...)

What is pow (0.,0.)?  I am getting a value 0 but shouldn't it be undefined?