coordinate frames transformation
This commit is contained in:
nuknal
266
pkg/calculator/eop.go
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266
pkg/calculator/eop.go
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@@ -0,0 +1,266 @@
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package calculator
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import (
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"bufio"
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"bytes"
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_ "embed"
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"fmt"
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"io"
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"math"
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"os"
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"strconv"
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"strings"
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"time"
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"github.com/hebl/gofa"
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)
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const (
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ARC_SECONDS_PER_RADIAN = 206264.80624709636
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)
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// https://www.iers.org/IERS/EN/DataProducts/EarthOrientationData/eop.html
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// https://maia.usno.navy.mil/ser7/finals2000A.all
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type EOPEntry struct {
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Year int
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Month int
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Day int
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MJD float64
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Xp float64 // 弧度 rad
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Yp float64 // 弧度 rad
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Dut1 float64
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}
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// https://earth-info.nga.mil/#eopp
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type EOPP5Line struct {
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Ta float64
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A, B float64
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C, D, P [2]float64
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E, F float64
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G, H, Q [2]float64
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Tb float64
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I, J float64
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K, L, R [4]float64
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}
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type EOPTable struct {
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URL string
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Local2000A string
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EOPs map[float64]*EOPEntry
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EOPP5Line EOPP5Line
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UseEOPP5Line bool
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}
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var EOP *EOPTable
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func NewEOPTable() *EOPTable {
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eop := &EOPTable{
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URL: "https://maia.usno.navy.mil/ser7/finals2000A.all",
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Local2000A: "data/EOP/finals2000A.all",
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EOPs: make(map[float64]*EOPEntry),
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UseEOPP5Line: false, // 当天使用 EOPP5Line 预测结果无法通过测试
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}
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return eop
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}
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func (eop *EOPTable) Load(eopData []byte, eopp5Line []byte) error {
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f, err := os.Open(eop.Local2000A)
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if err != nil {
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return eop.loadEmbed(eopData, eopp5Line)
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}
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defer f.Close()
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data, err := io.ReadAll(f)
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if err != nil {
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return eop.loadEmbed(eopData, eopp5Line)
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}
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return eop.loadEmbed(data, eopp5Line)
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}
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func (eop *EOPTable) loadEmbed(eopData []byte, eopp5Line []byte) error {
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reader := bufio.NewReader(bytes.NewReader(eopData))
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for {
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line, _, err := reader.ReadLine()
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if err == io.EOF {
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break
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}
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if err != nil {
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return err
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}
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var e EOPEntry
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if err := e.line2EOPEntry(line); err != nil {
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break
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}
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eop.EOPs[e.MJD] = &e
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}
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eop.EOPP5Line.parse(eopp5Line)
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return nil
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}
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func (eop EOPTable) Get(mjd float64) (*EOPEntry, bool) {
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e, ok := eop.EOPs[mjd]
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if !ok && eop.UseEOPP5Line {
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xp, yp, dut1 := eop.EOPP5Line.Predict(mjd)
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e = &EOPEntry{
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MJD: mjd,
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Xp: xp / ARC_SECONDS_PER_RADIAN,
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Yp: yp / ARC_SECONDS_PER_RADIAN,
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Dut1: dut1,
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}
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ok = true
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}
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return e, ok
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}
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func (eop EOPTable) GetByUTCTime(utctime time.Time) (*EOPEntry, bool) {
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var djm0, mjd float64
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gofa.Cal2jd(int(utctime.Year()), int(utctime.Month()), int(utctime.Day()), &djm0, &mjd)
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return eop.Get(mjd)
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}
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// https://maia.usno.navy.mil/ser7/readme.finals2000A
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// The format of the finals2000A.data, finals2000A.daily, and finals2000A.all files is:
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// Col.# Format Quantity
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// ------- ------ -------------------------------------------------------------
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// 1-2 I2 year (to get true calendar year, add 1900 for MJD<=51543 or add 2000 for MJD>=51544)
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// 3-4 I2 month number
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// 5-6 I2 day of month
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// 7 X [blank]
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// 8-15 F8.2 fractional Modified Julian Date (MJD UTC)
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// 16 X [blank]
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// 17 A1 IERS (I) or Prediction (P) flag for Bull. A polar motion values
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// 18 X [blank]
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// 19-27 F9.6 Bull. A PM-x (sec. of arc)
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// 28-36 F9.6 error in PM-x (sec. of arc)
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// 37 X [blank]
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// 38-46 F9.6 Bull. A PM-y (sec. of arc)
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// 47-55 F9.6 error in PM-y (sec. of arc)
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// 56-57 2X [blanks]
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// 58 A1 IERS (I) or Prediction (P) flag for Bull. A UT1-UTC values
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// 59-68 F10.7 Bull. A UT1-UTC (sec. of time)
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// 69-78 F10.7 error in UT1-UTC (sec. of time)
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// 79 X [blank]
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// 80-86 F7.4 Bull. A LOD (msec. of time) -- NOT ALWAYS FILLED
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// 87-93 F7.4 error in LOD (msec. of time) -- NOT ALWAYS FILLED
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// 94-95 2X [blanks]
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// 96 A1 IERS (I) or Prediction (P) flag for Bull. A nutation values
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// 97 X [blank]
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// 98-106 F9.3 Bull. A dX wrt IAU2000A Nutation (msec. of arc), Free Core Nutation NOT Removed
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// 107-115 F9.3 error in dX (msec. of arc)
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// 116 X [blank]
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// 117-125 F9.3 Bull. A dY wrt IAU2000A Nutation (msec. of arc), Free Core Nutation NOT Removed
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// 126-134 F9.3 error in dY (msec. of arc)
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// 135-144 F10.6 Bull. B PM-x (sec. of arc)
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// 145-154 F10.6 Bull. B PM-y (sec. of arc)
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// 155-165 F11.7 Bull. B UT1-UTC (sec. of time)
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// 166-175 F10.3 Bull. B dX wrt IAU2000A Nutation (msec. of arc)
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// 176-185 F10.3 Bull. B dY wrt IAU2000A Nutation (msec. of arc)
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func (e *EOPEntry) line2EOPEntry(line []byte) error {
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if len(line) < 68 {
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return fmt.Errorf("invalid eop line")
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}
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e.Year, _ = strconv.Atoi(string(line[0:2]))
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e.Month, _ = strconv.Atoi(strings.TrimSpace(string(line[2:4])))
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e.Day, _ = strconv.Atoi(strings.TrimSpace(string(line[4:6])))
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e.MJD, _ = strconv.ParseFloat(string(line[7:15]), 64)
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e.Xp, _ = strconv.ParseFloat(strings.TrimSpace(string(line[18:27])), 64)
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e.Yp, _ = strconv.ParseFloat(strings.TrimSpace(string(line[37:46])), 64)
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e.Xp = e.Xp / ARC_SECONDS_PER_RADIAN
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e.Yp = e.Yp / ARC_SECONDS_PER_RADIAN
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e.Dut1, _ = strconv.ParseFloat(strings.TrimSpace(string(line[58:68])), 64)
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return nil
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}
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func (e *EOPP5Line) parse(eopp5Line []byte) error {
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e.P[0] = 1.0
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e.P[1] = 1.0
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for i := 0; i < 4; i++ {
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e.R[i] = 1.0
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}
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reader := bufio.NewReader(bytes.NewReader(eopp5Line))
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var lines [][]byte
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for {
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line, _, err := reader.ReadLine()
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if err == io.EOF {
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break
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}
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if err != nil {
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return err
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}
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lines = append(lines, line)
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}
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if len(lines) < 5 {
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return fmt.Errorf("invalid eopp5 lines")
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}
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e.Ta, _ = strconv.ParseFloat(strings.TrimSpace(string(lines[0][0:10])), 64)
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e.A, _ = strconv.ParseFloat(strings.TrimSpace(string(lines[0][10:20])), 64)
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e.B, _ = strconv.ParseFloat(strings.TrimSpace(string(lines[0][20:30])), 64)
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e.C[0], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[0][30:40])), 64)
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e.C[1], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[0][40:50])), 64)
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e.D[0], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[0][50:60])), 64)
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e.D[1], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[0][60:70])), 64)
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e.P[0], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[0][70:76])), 64)
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e.P[1], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[1][0:6])), 64)
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e.E, _ = strconv.ParseFloat(strings.TrimSpace(string(lines[1][6:16])), 64)
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e.F, _ = strconv.ParseFloat(strings.TrimSpace(string(lines[1][16:26])), 64)
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e.G[0], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[1][26:36])), 64)
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e.G[1], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[1][36:46])), 64)
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e.H[0], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[1][46:56])), 64)
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e.H[1], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[1][56:66])), 64)
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e.Q[0], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[1][66:72])), 64)
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e.Q[1], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[1][72:78])), 64)
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e.Tb, _ = strconv.ParseFloat(strings.TrimSpace(string(lines[2][0:10])), 64)
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e.I, _ = strconv.ParseFloat(strings.TrimSpace(string(lines[2][10:20])), 64)
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e.J, _ = strconv.ParseFloat(strings.TrimSpace(string(lines[2][20:30])), 64)
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e.K[0], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[2][30:40])), 64)
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e.K[1], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[2][40:50])), 64)
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e.K[2], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[2][50:60])), 64)
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e.K[3], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[2][60:70])), 64)
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e.L[0], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[3][0:10])), 64)
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e.L[1], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[3][10:20])), 64)
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e.L[2], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[3][20:30])), 64)
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e.L[3], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[3][30:40])), 64)
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e.R[0], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[3][40:49])), 64)
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e.R[1], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[3][49:58])), 64)
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e.R[2], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[3][58:67])), 64)
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e.R[3], _ = strconv.ParseFloat(strings.TrimSpace(string(lines[3][67:76])), 64)
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return nil
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}
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// https://earth-info.nga.mil/php/download.php?file=gnss-eopp
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func (e *EOPP5Line) Predict(mjd float64) (xp, yp, dut1 float64) {
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xp = e.A + e.B*(mjd-e.Ta) +
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e.C[0]*math.Sin(2*math.Pi*(mjd-e.Ta)/e.P[0]) + e.D[0]*math.Cos(2*math.Pi*(mjd-e.Ta)/e.P[0]) +
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e.C[1]*math.Sin(2*math.Pi*(mjd-e.Ta)/e.P[1]) + e.D[1]*math.Cos(2*math.Pi*(mjd-e.Ta)/e.P[1])
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yp = e.E + e.F*(mjd-e.Ta) +
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e.G[0]*math.Sin(2*math.Pi*(mjd-e.Ta)/e.Q[0]) + e.H[0]*math.Cos(2*math.Pi*(mjd-e.Ta)/e.Q[0]) +
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e.G[1]*math.Sin(2*math.Pi*(mjd-e.Ta)/e.Q[1]) + e.H[1]*math.Cos(2*math.Pi*(mjd-e.Ta)/e.Q[1])
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dut1 = e.I + e.J*(mjd-e.Tb) +
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e.K[0]*math.Sin(2*math.Pi*(mjd-e.Tb)/e.R[0]) + e.L[0]*math.Cos(2*math.Pi*(mjd-e.Tb)/e.R[0]) +
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e.K[1]*math.Sin(2*math.Pi*(mjd-e.Tb)/e.R[1]) + e.L[1]*math.Cos(2*math.Pi*(mjd-e.Tb)/e.R[1]) +
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e.K[2]*math.Sin(2*math.Pi*(mjd-e.Tb)/e.R[2]) + e.L[2]*math.Cos(2*math.Pi*(mjd-e.Tb)/e.R[2]) +
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e.K[3]*math.Sin(2*math.Pi*(mjd-e.Tb)/e.R[3]) + e.L[3]*math.Cos(2*math.Pi*(mjd-e.Tb)/e.R[3])
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return
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}
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