add numerical recipes library

lib/nr/k_and_r/recipes/bcuint.c

@@ -0,0 +1,27 @@
+
+#include "nrutil.h"
+
+void bcuint(y,y1,y2,y12,x1l,x1u,x2l,x2u,x1,x2,ansy,ansy1,ansy2)
+float *ansy,*ansy1,*ansy2,x1,x1l,x1u,x2,x2l,x2u,y12[],y1[],y2[],y[];
+{
+	void bcucof();
+	int i;
+	float t,u,d1,d2,**c;
+
+	c=matrix(1,4,1,4);
+	d1=x1u-x1l;
+	d2=x2u-x2l;
+	bcucof(y,y1,y2,y12,d1,d2,c);
+	if (x1u == x1l || x2u == x2l) nrerror("Bad input in routine bcuint");
+	t=(x1-x1l)/d1;
+	u=(x2-x2l)/d2;
+	*ansy=(*ansy2)=(*ansy1)=0.0;
+	for (i=4;i>=1;i--) {
+		*ansy=t*(*ansy)+((c[i][4]*u+c[i][3])*u+c[i][2])*u+c[i][1];
+		*ansy2=t*(*ansy2)+(3.0*c[i][4]*u+2.0*c[i][3])*u+c[i][2];
+		*ansy1=u*(*ansy1)+(3.0*c[4][i]*t+2.0*c[3][i])*t+c[2][i];
+	}
+	*ansy1 /= d1;
+	*ansy2 /= d2;
+	free_matrix(c,1,4,1,4);
+}