From 6ff76468b49d4c4e1dc3669082a72c29aa3fcffe Mon Sep 17 00:00:00 2001
From: starainrt <i@b612.me>
Date: Sun, 23 Jul 2023 11:56:05 +0800
Subject: [PATCH] =?UTF-8?q?feature=20add:=E5=85=81=E8=AE=B8=E8=87=AA?=
 =?UTF-8?q?=E5=AE=9A=E4=B9=89deltaT?=
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---
 basic/calendar.go | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/basic/calendar.go b/basic/calendar.go
index 57297fd..96f3306 100644
--- a/basic/calendar.go
+++ b/basic/calendar.go
@@ -7,6 +7,8 @@ import (
 	"time"
 )
 
+var defDeltaTFn = DefaultDeltaT
+
 /*
 @name: 儒略日计算
 @dec: 计算给定时间的儒略日，1582年改力后为格里高利历，之前为儒略历
@@ -91,7 +93,36 @@ func dt_cal(y float64) float64 { //传入年， 返回世界时UT与原子时（
 	res := d[i+1] + d[i+2]*t1 + d[i+3]*t2 + d[i+4]*t3
 	return (res)
 }
-func DeltaT(Date float64, IsJDE bool) (Result float64) { //传入年或儒略日，传出为秒
+
+func DeltaT(date float64, isJDE bool) float64 {
+	return defDeltaTFn(date, isJDE)
+}
+
+func SetDeltaTFn(fn func(float64, bool) float64) {
+	if fn != nil {
+		defDeltaTFn = fn
+	}
+}
+
+func GetDeltaTFn() func(float64, bool) float64 {
+	return defDeltaTFn
+}
+
+func OldDefaultDeltaT(Date float64, IsJDE bool) (Result float64) { //传入年或儒略日，传出为秒
+	var Year float64
+	if IsJDE {
+		dates := JDE2Date(Date)
+		Year = float64(dates.Year()) + float64(dates.YearDay())/365.0
+	} else {
+		Year = Date
+	}
+	if Year < 2100 && Year >= 2010 {
+		return dt_cal(Year)
+	}
+	return DefaultDeltaT(Date, IsJDE)
+}
+
+func DefaultDeltaT(Date float64, IsJDE bool) (Result float64) { //传入年或儒略日，传出为秒
 	var Year float64
 	if IsJDE {
 		dates := JDE2Date(Date)
@@ -120,6 +151,7 @@ func DeltaT(Date float64, IsJDE bool) (Result float64) { //传入年或儒略日
 	}
 	return
 }
+
 func TD2UT(JDE float64, UT2TD bool) float64 { // true 世界时转力学时CC，false 力学时转世界时VV
 
 	Deltat := DeltaT(JDE, true)