add numerical recipes library

2025-09-12 18:55:25 +09:00
parent d4dff245bd
commit 2c75620ec9
1344 changed files with 63869 additions and 0 deletions
--- a/lib/nr/cpp/recipes/fourn.cpp
+++ b/lib/nr/cpp/recipes/fourn.cpp
@@ -0,0 +1,67 @@
+#include <cmath>
+#include "nr.h"
+using namespace std;
+
+void NR::fourn(Vec_IO_DP &data, Vec_I_INT &nn, const int isign)
+{
+	int idim,i1,i2,i3,i2rev,i3rev,ip1,ip2,ip3,ifp1,ifp2;
+	int ibit,k1,k2,n,nprev,nrem,ntot;
+	DP tempi,tempr,theta,wi,wpi,wpr,wr,wtemp;
+
+	int ndim=nn.size();
+	ntot=data.size()/2;
+	nprev=1;
+	for (idim=ndim-1;idim>=0;idim--) {
+		n=nn[idim];
+		nrem=ntot/(n*nprev);
+		ip1=nprev << 1;
+		ip2=ip1*n;
+		ip3=ip2*nrem;
+		i2rev=0;
+		for (i2=0;i2<ip2;i2+=ip1) {
+			if (i2 < i2rev) {
+				for (i1=i2;i1<i2+ip1-1;i1+=2) {
+					for (i3=i1;i3<ip3;i3+=ip2) {
+						i3rev=i2rev+i3-i2;
+						SWAP(data[i3],data[i3rev]);
+						SWAP(data[i3+1],data[i3rev+1]);
+					}
+				}
+			}
+			ibit=ip2 >> 1;
+			while (ibit >= ip1 && i2rev+1 > ibit) {
+				i2rev -= ibit;
+				ibit >>= 1;
+			}
+			i2rev += ibit;
+		}
+		ifp1=ip1;
+		while (ifp1 < ip2) {
+			ifp2=ifp1 << 1;
+			theta=isign*6.28318530717959/(ifp2/ip1);
+			wtemp=sin(0.5*theta);
+			wpr= -2.0*wtemp*wtemp;
+			wpi=sin(theta);
+			wr=1.0;
+			wi=0.0;
+			for (i3=0;i3<ifp1;i3+=ip1) {
+				for (i1=i3;i1<i3+ip1-1;i1+=2) {
+					for (i2=i1;i2<ip3;i2+=ifp2) {
+						k1=i2;
+						k2=k1+ifp1;
+						tempr=wr*data[k2]-wi*data[k2+1];
+						tempi=wr*data[k2+1]+wi*data[k2];
+						data[k2]=data[k1]-tempr;
+						data[k2+1]=data[k1+1]-tempi;
+						data[k1] += tempr;
+						data[k1+1] += tempi;
+					}
+				}
+				wr=(wtemp=wr)*wpr-wi*wpi+wr;
+				wi=wi*wpr+wtemp*wpi+wi;
+			}
+			ifp1=ifp2;
+		}
+		nprev *= n;
+	}
+}