add numerical recipes library

lib/nr/ansi/recipes/quadvl.c

@@ -0,0 +1,18 @@
+
+#define NRANSI
+#include "nrutil.h"
+
+void quadvl(float x, float y, float *fa, float *fb, float *fc, float *fd)
+{
+	float qa,qb,qc,qd;
+
+	qa=FMIN(2.0,FMAX(0.0,1.0-x));
+	qb=FMIN(2.0,FMAX(0.0,1.0-y));
+	qc=FMIN(2.0,FMAX(0.0,x+1.0));
+	qd=FMIN(2.0,FMAX(0.0,y+1.0));
+	*fa=0.25*qa*qb;
+	*fb=0.25*qb*qc;
+	*fc=0.25*qc*qd;
+	*fd=0.25*qd*qa;
+}
+#undef NRANSI