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/locate.cpp
+++ b/lib/nr/cpp/recipes/locate.cpp
@@ -0,0 +1,22 @@
+#include "nr.h"
+
+void NR::locate(Vec_I_DP &xx, const DP x, int &j)
+{
+	int ju,jm,jl;
+	bool ascnd;
+
+	int n=xx.size();
+	jl=-1;
+	ju=n;
+	ascnd=(xx[n-1] >= xx[0]);
+	while (ju-jl > 1) {
+		jm=(ju+jl) >> 1;
+		if (x >= xx[jm] == ascnd)
+			jl=jm;
+		else
+			ju=jm;
+	}
+	if (x == xx[0]) j=0;
+	else if (x == xx[n-1]) j=n-2;
+	else j=jl;
+}