add numerical recipes library

lib/nr/ansi/recipes/quad3d.c

@@ -0,0 +1,37 @@
+
+static float xsav,ysav;
+static float (*nrfunc)(float,float,float);
+
+float quad3d(float (*func)(float, float, float), float x1, float x2)
+{
+	float qgaus(float (*func)(float), float a, float b);
+	float f1(float x);
+
+	nrfunc=func;
+	return qgaus(f1,x1,x2);
+}
+
+float f1(float x)
+{
+	float qgaus(float (*func)(float), float a, float b);
+	float f2(float y);
+	float yy1(float),yy2(float);
+
+	xsav=x;
+	return qgaus(f2,yy1(x),yy2(x));
+}
+
+float f2(float y)
+{
+	float qgaus(float (*func)(float), float a, float b);
+	float f3(float z);
+	float z1(float,float),z2(float,float);
+
+	ysav=y;
+	return qgaus(f3,z1(xsav,y),z2(xsav,y));
+}
+
+float f3(float z)
+{
+	return (*nrfunc)(xsav,ysav,z);
+}