From math.h:

"Define _USE_MATH_DEFINES before including math.h to expose these
macro definitions for common math constants.  These are placed under
an #ifdef since these commonly-defined names are not part of the C/C++
standards."

So:

#define _USE_MATH_DEFINES
#include <math.h>

round() is not a C standard library function. You can create your own
simply:

double round(double x)
{
 return floor(x + .5);
}

Or, if you always want to round toward zero:

double round(double x)
{
 return x < 0 ? -floor(fabs(x) + .5) : floor(x + .5);
}

--
Phillip Crews aka Severian
Microsoft MVP, Windows SDK
Posting email address is real, but please post replies on the newsgroup.