add numerical recipes library

lib/nr/cpp/recipes/mppi.cpp

@@ -0,0 +1,56 @@
+#include <iostream>
+#include <iomanip>
+#include "nr.h"
+using namespace std;
+
+void NR::mppi(const int np)
+{
+	const unsigned int IAOFF=48,MACC=2;
+	int ir,j,n;
+	unsigned char mm;
+	string s;
+
+	n=np+MACC;
+	Vec_UCHR x(n),y(n),sx(n),sxi(n);
+	Vec_UCHR z(n),t(n),pi(n);
+	Vec_UCHR ss(2*n),tt(2*n);
+	t[0]=2;
+	for (j=1;j<n;j++) t[j]=0;
+	mpsqrt(x,x,t);
+	mpadd(pi,t,x);
+	mplsh(pi);
+	mpsqrt(sx,sxi,x);
+	mpmov(y,sx);
+	for (;;) {
+		mpadd(z,sx,sxi);
+		mplsh(z);
+		mpsdv(x,z,2,ir);
+		mpsqrt(sx,sxi,x);
+		mpmul(tt,y,sx);
+		mplsh(tt);
+		mpadd(tt,tt,sxi);
+		mplsh(tt);
+		x[0]++;
+		y[0]++;
+		mpinv(ss,y);
+		mpmul(y,tt,ss);
+		mplsh(y);
+		mpmul(tt,x,ss);
+		mplsh(tt);
+		mpmul(ss,pi,tt);
+		mplsh(ss);
+		mpmov(pi,ss);
+		mm=tt[0]-1;
+		for (j=1;j < n-1;j++)
+			if (tt[j] != mm) break;
+		if (j == n-1) {
+			cout << endl << "pi        = ";
+			s=pi[0]+IAOFF;
+			s += '.';
+			mp2dfr(pi,s);
+			s.erase(2.408*np,s.length());
+			cout << setw(64) << left << s << endl;
+			return;
+		}
+	}
+}