/* _______________________________________________________________ */

void global_statistics (void)

/* Calculates the mean and standard deviation for data points    */
/* in the array gpicval[512][512]                                */
/* uses several global variables for I/O, gmean,gstddev,gpicval, */
/* gmaxy,gmaxx                                                   */

{
float sum,sum2,temp;
int n,j,k;
sum=0.0;
sum2=0.0;
n=0;

        for (k=0;k<gmaxy;k++)
        for (j=0;j<gmaxx;j++)
                {
		temp= (float) gpicval[j][k];
		sum += temp;
		sum2 += temp*temp;
		n++;
                }

gmean=sum/((float) n);
gstddev=sqrt((sum2/((float) (n-1)))-(sum*sum)/(((float) n*(float) (n-1))));

}


/* _______________________________________________________________ */