add numerical recipes library

lib/nr/cpp/recipes/balanc.cpp

@@ -0,0 +1,45 @@
+#include <cmath>
+#include <limits>
+#include "nr.h"
+using namespace std;
+
+void NR::balanc(Mat_IO_DP &a)
+{
+	const DP RADIX = numeric_limits<DP>::radix;
+	int i,j,last=0;
+	DP s,r,g,f,c,sqrdx;
+
+	int n=a.nrows();
+	sqrdx=RADIX*RADIX;
+	while (last == 0) {
+		last=1;
+		for (i=0;i<n;i++) {
+			r=c=0.0;
+			for (j=0;j<n;j++)
+				if (j != i) {
+					c += fabs(a[j][i]);
+					r += fabs(a[i][j]);
+				}
+			if (c != 0.0 && r != 0.0) {
+				g=r/RADIX;
+				f=1.0;
+				s=c+r;
+				while (c<g) {
+					f *= RADIX;
+					c *= sqrdx;
+				}
+				g=r*RADIX;
+				while (c>g) {
+					f /= RADIX;
+					c /= sqrdx;
+				}
+				if ((c+r)/f < 0.95*s) {
+					last=0;
+					g=1.0/f;
+					for (j=0;j<n;j++) a[i][j] *= g;
+					for (j=0;j<n;j++) a[j][i] *= f;
+				}
+			}
+		}
+	}
+}