b612
2bf8478639
- 新增日月食中心带、偏食带、阴影足迹、等时线、食分线及升落边界计算，支持极区与混合食拓扑 - 新增日食单时刻阴影求解器、站心状态查询、批量采样和 ΔT 覆盖接口 - 重构恒星与行星月掩路径，补充有限盘面接触、站心修正、掩带宽度、极区投影及升落边界 - 扩展 SVG 与 GeoJSON 输出，支持详细面板、全球/极区/地球投影、边界闭合、时间标记和拓扑签名 - 扩展日月食候选搜索、局地搜索、沙罗序列预计算与范围外推，补充系列锚点和成员一致性校验 - 补齐古历纪年、儒略历独有闰日、多公历候选、历法改革跨日及精确日期运算接口 - 优化 ΔT、章动、恒星时、月球地平线、事件根搜索和本地星历缓存，降低重复计算开销并提升边界稳定
289 lines
9.1 KiB
Go
289 lines
9.1 KiB
Go
package eclipse
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import (
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"math"
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"sync"
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"b612.me/astro/basic"
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)
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const (
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sarosCycleLunations = 223
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sarosCycleDays = float64(sarosCycleLunations) * solarEclipseSynodicMonthDays
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// The generated tables show at most 90 members in one series. A window of
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// 90 returns therefore covers a complete series without evaluating remote
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// samples whose ancient ephemeris drift can reject an otherwise valid event.
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sarosExtrapolationWindow = 90
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sarosMagicYearOffset = 3000
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sarosMagicCountMask = 0x7f
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sarosMagicDayMask = 0x1f
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sarosMagicMonthMask = 0x0f
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sarosMagicYearMask = 0x1fff
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sarosMagicCountShift = 0
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sarosMagicDayShift = 7
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sarosMagicMonthShift = 12
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sarosMagicYearShift = 16
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sarosMagicMatchLimitDay = 12.0
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sarosMagicTieEpsilonDay = 1e-9
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)
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// SarosInfo 沙罗序列信息, Saros series metadata.
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type SarosInfo struct {
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// Series 是权威目录系列编号；Verified=false 时为根据周期外推得到的暂定编号。
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// Series is the authoritative catalog series number, or a provisional number when Verified is false.
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Series int
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// Member 是本次食在该系列中的序号，从 1 开始计数。
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// Member is the 1-based index of this eclipse within the series.
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Member int
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// Count 是该系列的总成员数。
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// Count is the total number of eclipses in the series.
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Count int
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// Verified 表示系列头和成员范围已与内置权威目录锚点核验。
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// Verified reports whether the series head and member range match an authoritative catalog anchor.
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Verified bool
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}
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// sarosAnchorRange is the authoritative member window of one series as
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// published in the anchor catalog. Extended (provisional) tables may enumerate
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// one or two extra members at the head and tail of a series, which collides
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// with the anchored numbering: the same member index then appears twice and the
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// series count changes mid-series. Reconciling against the anchor keeps the
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// member numbering and the total count consistent for every event.
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type sarosAnchorRange struct {
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headTT float64
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count int
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offset int
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}
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var (
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sarosAnchorRangesOnce sync.Once
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sarosAnchorRanges [2]map[int]sarosAnchorRange
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)
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func sarosAnchorRangeFor(phase, series int) (sarosAnchorRange, bool) {
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sarosAnchorRangesOnce.Do(buildSarosAnchorRanges)
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if phase < 0 || phase >= len(sarosAnchorRanges) {
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return sarosAnchorRange{}, false
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}
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value, ok := sarosAnchorRanges[phase][series]
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return value, ok
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}
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func buildSarosAnchorRanges() {
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anchors := solarSarosAnchors[:]
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base := 0
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overrides := solarSarosHeadOverrides[:]
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for phase := 0; phase < 2; phase++ {
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if phase == 1 {
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anchors = lunarSarosAnchors[:]
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base = 1
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overrides = lunarSarosHeadOverrides[:]
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}
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ranges := make(map[int]sarosAnchorRange, len(anchors)+len(overrides))
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for index, magic := range anchors {
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anchor := decodeSarosMagic(magic, base+index)
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headTT := basic.JDECalc(int(anchor.Year), int(anchor.Month), float64(anchor.Day))
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if math.IsNaN(headTT) {
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continue
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}
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ranges[int(anchor.Series)] = sarosAnchorRange{headTT: headTT, count: int(anchor.Count)}
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}
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for _, override := range overrides {
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headTT := basic.JDECalc(int(override.HeadYear), int(override.HeadMonth), float64(override.HeadDay))
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if math.IsNaN(headTT) {
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continue
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}
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ranges[int(override.Series)] = sarosAnchorRange{
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headTT: headTT,
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count: int(override.Count),
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offset: int(override.MemberOffset),
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}
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}
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sarosAnchorRanges[phase] = ranges
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}
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}
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// reconcileSarosSpan anchors a provisional member to the authoritative series
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// window. Members outside that window are not part of the catalog series, so
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// they report no Saros metadata instead of a conflicting provisional number.
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// The member index uses the same relation as the anchor matcher, which keeps a
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// provisional event and an anchored event of one series in step.
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func reconcileSarosSpan(info SarosInfo, ttJDE float64, phase int) (SarosInfo, bool) {
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anchor, ok := sarosAnchorRangeFor(phase, info.Series)
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if !ok {
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return info, true
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}
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member := int(math.Round((ttJDE-anchor.headTT)/sarosCycleDays)) + 1 + anchor.offset
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if member < 1 || member > anchor.count {
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return SarosInfo{}, false
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}
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info.Member = member
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info.Count = anchor.count
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return info, true
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}
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type sarosMagic uint32
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type sarosAnchor struct {
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Series int16
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Count uint8
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Year int16
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Month uint8
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Day uint8
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}
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type sarosHeadOverride struct {
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Series int16
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Count uint8
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HeadYear int16
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HeadMonth uint8
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HeadDay uint8
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MemberOffset int8
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}
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var solarSarosHeadOverrides = [...]sarosHeadOverride{
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{Series: 22, Count: 71, HeadYear: -2192, HeadMonth: 5, HeadDay: 17, MemberOffset: -1},
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}
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var lunarSarosHeadOverrides = [...]sarosHeadOverride{
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// 4 号锚表头提前了一个分支：目录成员 1 落在本模型认不出的浅半影回次上，
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// 头按目录记作第 3 个成员，尾部最后一场才与目录的 Count 对齐。
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{Series: 4, Count: 78, HeadYear: -2483, HeadMonth: 1, HeadDay: 12, MemberOffset: 2},
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{Series: 8, Count: 86, HeadYear: -2494, HeadMonth: 8, HeadDay: 7, MemberOffset: 0},
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{Series: 61, Count: 78, HeadYear: -762, HeadMonth: 12, HeadDay: 24, MemberOffset: 1},
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}
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func solarSarosInfo(ttJDE float64) (SarosInfo, bool) {
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if info, ok := matchSarosMagic(solarSarosAnchors[:], 0, solarSarosHeadOverrides[:], ttJDE); ok {
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return info, true
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}
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return reconciledSarosInfo(extendedSarosInfo, ttJDE, 0)
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}
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func lunarSarosInfo(ttJDE float64) (SarosInfo, bool) {
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if info, ok := matchSarosMagic(lunarSarosAnchors[:], 1, lunarSarosHeadOverrides[:], ttJDE); ok {
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return info, true
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}
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return reconciledSarosInfo(extendedSarosInfo, ttJDE, 1)
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}
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// reconciledSarosInfo applies the anchor window to a provisional lookup so the
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// public metadata never mixes two numbering baselines for one series.
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func reconciledSarosInfo(
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provisional func(float64, int) (SarosInfo, bool),
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ttJDE float64,
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phase int,
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) (SarosInfo, bool) {
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info, ok := provisional(ttJDE, phase)
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if !ok {
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return SarosInfo{}, false
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}
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return reconcileSarosSpan(info, ttJDE, phase)
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}
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func matchSarosMagic(anchors []sarosMagic, seriesBase int, overrides []sarosHeadOverride, ttJDE float64) (SarosInfo, bool) {
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if info, ok := matchSarosMagicOverrides(overrides, ttJDE); ok {
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return info, true
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}
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// 带 override 的序列只认 override 头，与 buildSarosAnchorRanges 的覆盖语义一致。
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bestDistance := math.Inf(1)
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best := SarosInfo{}
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for index, magic := range anchors {
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anchor := decodeSarosMagic(magic, seriesBase+index)
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if sarosSeriesOverridden(overrides, int(anchor.Series)) {
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continue
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}
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info, distance, ok := matchSarosMagicCandidate(ttJDE, anchor, 0)
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if !ok {
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continue
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}
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if betterSarosMagicMatch(info, distance, best, bestDistance) {
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bestDistance = distance
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best = info
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}
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}
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if bestDistance <= sarosMagicMatchLimitDay {
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return best, true
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}
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return SarosInfo{}, false
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}
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// sarosSeriesOverridden 报告该序列是否带有 override 头。
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func sarosSeriesOverridden(overrides []sarosHeadOverride, series int) bool {
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for _, override := range overrides {
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if int(override.Series) == series {
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return true
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}
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}
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return false
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}
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func matchSarosMagicOverrides(overrides []sarosHeadOverride, ttJDE float64) (SarosInfo, bool) {
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bestDistance := math.Inf(1)
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best := SarosInfo{}
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for _, override := range overrides {
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anchor := sarosAnchor{
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Series: override.Series,
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Count: override.Count,
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Year: override.HeadYear,
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Month: override.HeadMonth,
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Day: override.HeadDay,
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}
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info, distance, ok := matchSarosMagicCandidate(ttJDE, anchor, int(override.MemberOffset))
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if !ok {
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continue
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}
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if betterSarosMagicMatch(info, distance, best, bestDistance) {
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bestDistance = distance
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best = info
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}
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}
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if bestDistance <= sarosMagicMatchLimitDay {
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return best, true
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}
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return SarosInfo{}, false
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}
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func matchSarosMagicCandidate(ttJDE float64, anchor sarosAnchor, memberOffset int) (SarosInfo, float64, bool) {
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headTT := basic.JDECalc(int(anchor.Year), int(anchor.Month), float64(anchor.Day))
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if math.IsNaN(headTT) {
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return SarosInfo{}, 0, false
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}
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member := int(math.Round((ttJDE-headTT)/sarosCycleDays)) + 1 + memberOffset
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if member < 1 || member > int(anchor.Count) {
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return SarosInfo{}, 0, false
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}
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expectedTT := headTT + float64(member-1-memberOffset)*sarosCycleDays
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return SarosInfo{
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Series: int(anchor.Series),
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Member: member,
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Count: int(anchor.Count),
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Verified: true,
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}, math.Abs(ttJDE - expectedTT), true
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}
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func betterSarosMagicMatch(info SarosInfo, distance float64, best SarosInfo, bestDistance float64) bool {
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if distance < bestDistance-sarosMagicTieEpsilonDay {
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return true
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}
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if math.Abs(distance-bestDistance) > sarosMagicTieEpsilonDay {
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return false
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}
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if info.Series != best.Series {
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return info.Series < best.Series
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}
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return info.Member < best.Member
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}
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func decodeSarosMagic(magic sarosMagic, series int) sarosAnchor {
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value := uint32(magic)
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return sarosAnchor{
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Series: int16(series),
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Count: uint8((value >> sarosMagicCountShift) & sarosMagicCountMask),
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Year: int16(int((value>>sarosMagicYearShift)&sarosMagicYearMask) - sarosMagicYearOffset),
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Month: uint8((value >> sarosMagicMonthShift) & sarosMagicMonthMask),
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Day: uint8((value >> sarosMagicDayShift) & sarosMagicDayMask),
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}
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}
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