Return the closest int to the double argument.
The arithmetic is same with c/c++, but not same with Excel.
int nint( double x )
the nearest integer to x
double r1 = 3.6;
double r2 = 3.4;
printf("nearest integer to %f is %d\nnearest integer to %f is %d\n", r1, nint(r1), r2, nint(r2));