+ case VDEF_LSLSLOPE:
+ case VDEF_LSLINT:
+ case VDEF_LSLCORREL:{
+ /* Bestfit line by linear least squares method */
+
+ int cnt=0;
+ double SUMx, SUMy, SUMxy, SUMxx, SUMyy, slope, y_intercept, correl ;
+ SUMx = 0; SUMy = 0; SUMxy = 0; SUMxx = 0; SUMyy = 0;
+
+ for (step=0;step<steps;step++) {
+ if (finite(data[step*src->ds_cnt])) {
+ cnt++;
+ SUMx += step;
+ SUMxx += step * step;
+ SUMxy += step * data[step*src->ds_cnt];
+ SUMy += data[step*src->ds_cnt];
+ SUMyy += data[step*src->ds_cnt]*data[step*src->ds_cnt];
+ };
+ }
+
+ slope = ( SUMx*SUMy - cnt*SUMxy ) / ( SUMx*SUMx - cnt*SUMxx );
+ y_intercept = ( SUMy - slope*SUMx ) / cnt;
+ correl = (SUMxy - (SUMx*SUMy)/cnt) / sqrt((SUMxx - (SUMx*SUMx)/cnt)*(SUMyy - (SUMy*SUMy)/cnt));
+
+ if (cnt) {
+ if (dst->vf.op == VDEF_LSLSLOPE) {
+ dst->vf.val = slope;
+ dst->vf.when = cnt*src->step;
+ } else if (dst->vf.op == VDEF_LSLINT) {
+ dst->vf.val = y_intercept;
+ dst->vf.when = cnt*src->step;
+ } else if (dst->vf.op == VDEF_LSLCORREL) {
+ dst->vf.val = correl;
+ dst->vf.when = cnt*src->step;
+ };
+
+ } else {
+ dst->vf.val = DNAN;
+ dst->vf.when = 0;
+ }
+ }
+ break;