#include <math.h>
#define pi 3.141592653589793

/* gauss_mask - to create a one-dimensional gaussian mask
**              of width "sigma" on "Hsize" pixels.
**              The value of the mask are scaled so that the
**              sum-of-mask=1.0
*/
 
Gauss(s,Hsize,H)
int Hsize;
float s,*H;
{
  int     i;
  float  cst,tssq,x,sum;
 
  cst=1./(s*sqrt(2.0*pi)) ;
  tssq=1./(2*s*s) ;
 
  for(i=0; i<Hsize; i++) {
    x=(float)(i-Hsize/2);
    H[i]=(cst*exp(-(x*x*tssq))) ;
  }
 
  sum=0.0;
  for(i=0;i<Hsize;i++)
    sum += H[i];
  for(i=0;i<Hsize;i++)
    H[i] /= sum;
}