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/k_and_r/recipes/tridag.c
+++ b/lib/nr/k_and_r/recipes/tridag.c
@@ -0,0 +1,23 @@
+
+#include "nrutil.h"
+
+void tridag(a,b,c,r,u,n)
+float a[],b[],c[],r[],u[];
+unsigned long n;
+{
+	unsigned long j;
+	float bet,*gam;
+
+	gam=vector(1,n);
+	if (b[1] == 0.0) nrerror("Error 1 in tridag");
+	u[1]=r[1]/(bet=b[1]);
+	for (j=2;j<=n;j++) {
+		gam[j]=c[j-1]/bet;
+		bet=b[j]-a[j]*gam[j];
+		if (bet == 0.0)	nrerror("Error 2 in tridag");
+		u[j]=(r[j]-a[j]*u[j-1])/bet;
+	}
+	for (j=(n-1);j>=1;j--)
+		u[j] -= gam[j+1]*u[j+1];
+	free_vector(gam,1,n);
+}