/* **************************** */
/* First derivative of Gaussian */
/* **************************** */

#define pi 3.141592653589793

Gauss_deriv1(s,Hsize,H)
int Hsize;
float s, *H;
{
  int     i;
  float  x,cst,tssq;

  cst=1./(s*s*s*sqrt(2.0*pi)) ;
  tssq= -1./(2.0*s*s) ;

  for(i=0; i<Hsize; i++) {
    x=(float)(i-Hsize/2);
    H[i] =-x*cst*exp(x*x*tssq);
  }
}