add numerical recipes library

lib/nr/cpp/recipes/rotate.cpp

@@ -0,0 +1,36 @@
+#include <cmath>
+#include "nr.h"
+using namespace std;
+
+void NR::rotate(Mat_IO_DP &r, Mat_IO_DP &qt, const int i, const DP a,
+	const DP b)
+{
+	int j;
+	DP c,fact,s,w,y;
+
+	int n=r.nrows();
+	if (a == 0.0) {
+		c=0.0;
+		s=(b >= 0.0 ? 1.0 : -1.0);
+	} else if (fabs(a) > fabs(b)) {
+		fact=b/a;
+		c=SIGN(1.0/sqrt(1.0+(fact*fact)),a);
+		s=fact*c;
+	} else {
+		fact=a/b;
+		s=SIGN(1.0/sqrt(1.0+(fact*fact)),b);
+		c=fact*s;
+	}
+	for (j=i;j<n;j++) {
+		y=r[i][j];
+		w=r[i+1][j];
+		r[i][j]=c*y-s*w;
+		r[i+1][j]=s*y+c*w;
+	}
+	for (j=0;j<n;j++) {
+		y=qt[i][j];
+		w=qt[i+1][j];
+		qt[i][j]=c*y-s*w;
+		qt[i+1][j]=s*y+c*w;
+	}
+}