The R Project SVN – R – Diff – /trunk/src/appl/splines.c

 void spline_coef(int *method, int *n, double *x, double *y,
 		 double *b, double *c, double *d, double *e)
+{
     switch(*method) {
     case 1:
-	periodic_spline(*n, x, y, b, c, d, e);
+	periodic_spline(*n, x, y, b, c, d, e);	break;
-	break;
     case 2:
-	natural_spline(*n, x, y, b, c, d);
+	natural_spline(*n, x, y, b, c, d);	break;
-	break;
     case 3:
-	fmm_spline(*n, x, y, b, c, d);
+	fmm_spline(*n, x, y, b, c, d);	break;
-	break;
+    }
+}
 void spline_eval(int *method, int *nu, double *u, double *v,
 		 int *n, double *x, double *y, double *b, double *c, double *d)
+{
+/* Evaluate  v[l] := spline(u[l], ...),  l = 1,..,nu */
     int i, j, k, l;
     double ul, dx, tmp;
-    u--; v--;
-    x--; y--;
-    b--; c--; d--;
-    if(*method == 1) {
+    if(*method == 1 && *n > 1) {
-	dx = x[*n] - x[1];
+	dx = x[*n - 1] - x[0];
-	for( l=1 ; l<=*nu ; l++) {
+	for(l = 0; l < *nu; l++) {
-	    v[l] = fmod(u[l]-x[1], dx);
+	    v[l] = fmod(u[l]-x[0], dx);
 	    if(v[l] < 0.0) v[l] += dx;
-	    v[l] = v[l] + x[1];
+	    v[l] += x[0];
+	}
+    }
     else {
-	for( l=1 ; l<=*nu ; l++)
+	for(l =0; l < *nu; l++)
 	    v[l] = u[l];
+    }
-    i = 1;
+    i = 0;
-    for( l=1 ; l<=*nu ; l++) {
+    for(l = 0; l < *nu; l++) {
 	ul = v[l];
 	if(ul < x[i] || x[i+1] < ul) {
-	    i = 1;
+	    i = 0;
-	    j = *n + 1;
+	    j = *n;
 	    do {
 		k = (i+j)/2;
 		if(ul < x[k]) j = k;
 		else i = k;
+	    }
 	    while(j > i+1);
+	}
 	dx = ul - x[i];
 	/* for natural splines extrapolate linearly left */
-	tmp = d[i];
-	if(*method == 2 && ul < x[1]) tmp = 0.0;
+	tmp = (*method == 2 && ul < x[0]) ? 0.0 : d[i];
 	v[l] = y[i] + dx*(b[i] + dx*(c[i] + dx*tmp));
+    }
+}

The R Project SVN R

(root)/trunk/src/appl/splines.c @ 34412 – Rev 25962 → 31434