add numerical recipes library

lib/nr/cpp/recipes/qrsolv.cpp

@@ -0,0 +1,15 @@
+#include "nr.h"
+
+void NR::qrsolv(Mat_I_DP &a, Vec_I_DP &c, Vec_I_DP &d, Vec_IO_DP &b)
+{
+	int i,j;
+	DP sum,tau;
+
+	int n=a.nrows();
+	for (j=0;j<n-1;j++) {
+		for (sum=0.0,i=j;i<n;i++) sum += a[i][j]*b[i];
+		tau=sum/c[j];
+		for (i=j;i<n;i++) b[i] -= tau*a[i][j];
+	}
+	rsolv(a,d,b);
+}