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/* Huge speed optimization posible:
Replace corelation matrix on square of correlation matrix, it will
remove need of cpu-consuming sqrt function
*/
#include <math.h>
struct _disp {
unsigned long disp_n;
unsigned long disp_s;
double disp_d;
double disp_m;
};
typedef struct _disp *disp;
disp disp_init() {
disp d = (disp)malloc(sizeof(struct _disp));
d->disp_n=0;
d->disp_s=0;
d->disp_d=0;
return d;
}
void disp_deinit(disp d) {
free(d);
}
void disp_event(disp d,unsigned long disp_v) {
unsigned long t;
d->disp_n++;
t=d->disp_n*(d->disp_n-1);
d->disp_s+=disp_v;
disp_v*=d->disp_n;
if (t) d->disp_d+=(double)(((d->disp_s-disp_v)*(d->disp_s-disp_v)))/t;
}
void disp_post(disp d) {
if (d->disp_n>0) {
d->disp_m = ((double)d->disp_s) / d->disp_n;
if (d->disp_n>1) {
d->disp_d /= (d->disp_n-1);
d->disp_d = sqrt(d->disp_d);
}
}
}
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