add numerical recipes library

lib/nr/ansi/recipes/qrupdt.c

@@ -0,0 +1,26 @@
+
+#include <math.h>
+#define NRANSI
+#include "nrutil.h"
+
+void qrupdt(float **r, float **qt, int n, float u[], float v[])
+{
+	void rotate(float **r, float **qt, int n, int i, float a, float b);
+	int i,j,k;
+
+	for (k=n;k>=1;k--) {
+		if (u[k]) break;
+	}
+	if (k < 1) k=1;
+	for (i=k-1;i>=1;i--) {
+		rotate(r,qt,n,i,u[i],-u[i+1]);
+		if (u[i] == 0.0) u[i]=fabs(u[i+1]);
+		else if (fabs(u[i]) > fabs(u[i+1]))
+			u[i]=fabs(u[i])*sqrt(1.0+SQR(u[i+1]/u[i]));
+		else u[i]=fabs(u[i+1])*sqrt(1.0+SQR(u[i]/u[i+1]));
+	}
+	for (j=1;j<=n;j++) r[1][j] += u[1]*v[j];
+	for (i=1;i<k;i++)
+		rotate(r,qt,n,i,r[i][i],-r[i+1][i]);
+}
+#undef NRANSI