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/caldat.cpp
+++ b/lib/nr/cpp/recipes/caldat.cpp
@@ -0,0 +1,28 @@
+#include <cmath>
+#include "nr.h"
+using namespace std;
+
+void NR::caldat(const int julian, int &mm, int &id, int &iyyy)
+{
+	const int IGREG=2299161;
+	int ja,jalpha,jb,jc,jd,je;
+
+	if (julian >= IGREG) {
+		jalpha=int((DP(julian-1867216)-0.25)/36524.25);
+		ja=julian+1+jalpha-int(0.25*jalpha);
+	} else if (julian < 0) {
+		ja=julian+36525*(1-julian/36525);
+	} else
+		ja=julian;
+	jb=ja+1524;
+	jc=int(6680.0+(DP(jb-2439870)-122.1)/365.25);
+	jd=int(365*jc+(0.25*jc));
+	je=int((jb-jd)/30.6001);
+	id=jb-jd-int(30.6001*je);
+	mm=je-1;
+	if (mm > 12) mm -= 12;
+	iyyy=jc-4715;
+	if (mm > 2) --iyyy;
+	if (iyyy <= 0) --iyyy;
+	if (julian < 0) iyyy -= 100*(1-julian/36525);
+}