add numerical recipes library

lib/nr/k_and_r/recipes/balanc.c

@@ -0,0 +1,46 @@
+
+#include <math.h>
+#define RADIX 2.0
+
+void balanc(a,n)
+float **a;
+int n;
+{
+	int last,j,i;
+	float s,r,g,f,c,sqrdx;
+
+	sqrdx=RADIX*RADIX;
+	last=0;
+	while (last == 0) {
+		last=1;
+		for (i=1;i<=n;i++) {
+			r=c=0.0;
+			for (j=1;j<=n;j++)
+				if (j != i) {
+					c += fabs(a[j][i]);
+					r += fabs(a[i][j]);
+				}
+			if (c && r) {
+				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=1;j<=n;j++) a[i][j] *= g;
+					for (j=1;j<=n;j++) a[j][i] *= f;
+				}
+			}
+		}
+	}
+}
+#undef RADIX