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Version 2.0.3.
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@ezze
ezze committed Sep 15, 2018
2 parents 7b3dbe3 + b60f30c commit a02152d
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4 changes: 4 additions & 0 deletions CHANGELOG.md
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@@ -1,5 +1,9 @@
## Changelog

### 2.0.3 (2018-09-15)

- `satrec` object is not cloned in `sgp4` and `sg4init` functions due to performance reasons.

### 2.0.2 (2018-04-16)

- [Wrong predictions for Molniya 3-47 orbits](https://github.com/shashwatak/satellite-js/issues/43) are fixed. Special
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2 changes: 1 addition & 1 deletion package.json
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@@ -1,6 +1,6 @@
{
"name": "satellite.js",
"version": "2.0.2",
"version": "2.0.3",
"description": "SGP4/SDP4 calculation library",
"main": "lib/index.js",
"jsnext:main": "dist/satellite.es.js",
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4 changes: 3 additions & 1 deletion src/io.js
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Expand Up @@ -144,7 +144,7 @@ export default function twoline2satrec(longstr1, longstr2) {
satrec.jdsatepoch = jday(year, mon, day, hr, minute, sec);

// ---------------- initialize the orbit at sgp4epoch -------------------
return sgp4init(satrec, {
sgp4init(satrec, {
opsmode,
satn: satrec.satnum,
epoch: satrec.jdsatepoch - 2433281.5,
Expand All @@ -156,4 +156,6 @@ export default function twoline2satrec(longstr1, longstr2) {
xno: satrec.no,
xnodeo: satrec.nodeo,
});

return satrec;
}
164 changes: 82 additions & 82 deletions src/propagation/sgp4.js
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Expand Up @@ -98,7 +98,7 @@ import dspace from './dspace';
* vallado, crawford, hujsak, kelso 2006
----------------------------------------------------------------------------*/
export default function sgp4(satrec, tsince) {
const rec = { ...satrec };
/* eslint-disable no-param-reassign */

let coseo1;
let sineo1;
Expand Down Expand Up @@ -138,76 +138,76 @@ export default function sgp4(satrec, tsince) {
const vkmpersec = (earthRadius * xke) / 60.0;

// --------------------- clear sgp4 error flag -----------------
rec.t = tsince;
rec.error = 0;
satrec.t = tsince;
satrec.error = 0;

// ------- update for secular gravity and atmospheric drag -----
const xmdf = rec.mo + (rec.mdot * rec.t);
const argpdf = rec.argpo + (rec.argpdot * rec.t);
const nodedf = rec.nodeo + (rec.nodedot * rec.t);
const xmdf = satrec.mo + (satrec.mdot * satrec.t);
const argpdf = satrec.argpo + (satrec.argpdot * satrec.t);
const nodedf = satrec.nodeo + (satrec.nodedot * satrec.t);
argpm = argpdf;
mm = xmdf;
const t2 = rec.t * rec.t;
nodem = nodedf + (rec.nodecf * t2);
tempa = 1.0 - (rec.cc1 * rec.t);
tempe = rec.bstar * rec.cc4 * rec.t;
templ = rec.t2cof * t2;

if (rec.isimp !== 1) {
delomg = rec.omgcof * rec.t;
const t2 = satrec.t * satrec.t;
nodem = nodedf + (satrec.nodecf * t2);
tempa = 1.0 - (satrec.cc1 * satrec.t);
tempe = satrec.bstar * satrec.cc4 * satrec.t;
templ = satrec.t2cof * t2;

if (satrec.isimp !== 1) {
delomg = satrec.omgcof * satrec.t;
// sgp4fix use mutliply for speed instead of pow
const delmtemp = 1.0 + (rec.eta * Math.cos(xmdf));
delm = rec.xmcof * ((delmtemp * delmtemp * delmtemp) - rec.delmo);
const delmtemp = 1.0 + (satrec.eta * Math.cos(xmdf));
delm = satrec.xmcof * ((delmtemp * delmtemp * delmtemp) - satrec.delmo);
temp = delomg + delm;
mm = xmdf + temp;
argpm = argpdf - temp;
t3 = t2 * rec.t;
t4 = t3 * rec.t;
tempa = tempa - (rec.d2 * t2) - (rec.d3 * t3) - (rec.d4 * t4);
tempe += rec.bstar * rec.cc5 * (Math.sin(mm) - rec.sinmao);
templ = templ + (rec.t3cof * t3) + (t4 * (rec.t4cof + (rec.t * rec.t5cof)));
t3 = t2 * satrec.t;
t4 = t3 * satrec.t;
tempa = tempa - (satrec.d2 * t2) - (satrec.d3 * t3) - (satrec.d4 * t4);
tempe += satrec.bstar * satrec.cc5 * (Math.sin(mm) - satrec.sinmao);
templ = templ + (satrec.t3cof * t3) + (t4 * (satrec.t4cof + (satrec.t * satrec.t5cof)));
}
nm = rec.no;
let em = rec.ecco;
inclm = rec.inclo;
if (rec.method === 'd') {
tc = rec.t;
nm = satrec.no;
let em = satrec.ecco;
inclm = satrec.inclo;
if (satrec.method === 'd') {
tc = satrec.t;

const dspaceOptions = {
irez: rec.irez,
d2201: rec.d2201,
d2211: rec.d2211,
d3210: rec.d3210,
d3222: rec.d3222,
d4410: rec.d4410,
d4422: rec.d4422,
d5220: rec.d5220,
d5232: rec.d5232,
d5421: rec.d5421,
d5433: rec.d5433,
dedt: rec.dedt,
del1: rec.del1,
del2: rec.del2,
del3: rec.del3,
didt: rec.didt,
dmdt: rec.dmdt,
dnodt: rec.dnodt,
domdt: rec.domdt,
argpo: rec.argpo,
argpdot: rec.argpdot,
t: rec.t,
irez: satrec.irez,
d2201: satrec.d2201,
d2211: satrec.d2211,
d3210: satrec.d3210,
d3222: satrec.d3222,
d4410: satrec.d4410,
d4422: satrec.d4422,
d5220: satrec.d5220,
d5232: satrec.d5232,
d5421: satrec.d5421,
d5433: satrec.d5433,
dedt: satrec.dedt,
del1: satrec.del1,
del2: satrec.del2,
del3: satrec.del3,
didt: satrec.didt,
dmdt: satrec.dmdt,
dnodt: satrec.dnodt,
domdt: satrec.domdt,
argpo: satrec.argpo,
argpdot: satrec.argpdot,
t: satrec.t,
tc,
gsto: rec.gsto,
xfact: rec.xfact,
xlamo: rec.xlamo,
no: rec.no,
atime: rec.atime,
gsto: satrec.gsto,
xfact: satrec.xfact,
xlamo: satrec.xlamo,
no: satrec.no,
atime: satrec.atime,
em,
argpm,
inclm,
xli: rec.xli,
xli: satrec.xli,
mm,
xni: rec.xni,
xni: satrec.xni,
nodem,
nm,
};
Expand All @@ -226,7 +226,7 @@ export default function sgp4(satrec, tsince) {

if (nm <= 0.0) {
// printf("// error nm %f\n", nm);
rec.error = 2;
satrec.error = 2;
// sgp4fix add return
return [false, false];
}
Expand All @@ -239,7 +239,7 @@ export default function sgp4(satrec, tsince) {
// sgp4fix am is fixed from the previous nm check
if (em >= 1.0 || em < -0.001) { // || (am < 0.95)
// printf("// error em %f\n", em);
rec.error = 1;
satrec.error = 1;
// sgp4fix to return if there is an error in eccentricity
return [false, false];
}
Expand All @@ -248,7 +248,7 @@ export default function sgp4(satrec, tsince) {
if (em < 1.0e-6) {
em = 1.0e-6;
}
mm += rec.no * templ;
mm += satrec.no * templ;
xlm = mm + argpm + nodem;

nodem %= twoPi;
Expand All @@ -268,19 +268,19 @@ export default function sgp4(satrec, tsince) {
mp = mm;
sinip = sinim;
cosip = cosim;
if (rec.method === 'd') {
if (satrec.method === 'd') {
const dpperParameters = {
inclo: rec.inclo,
inclo: satrec.inclo,
init: 'n',
ep,
inclp: xincp,
nodep,
argpp,
mp,
opsmode: rec.operationmod,
opsmode: satrec.operationmod,
};

const dpperResult = dpper(rec, dpperParameters);
const dpperResult = dpper(satrec, dpperParameters);

({
ep,
Expand All @@ -298,30 +298,30 @@ export default function sgp4(satrec, tsince) {
}
if (ep < 0.0 || ep > 1.0) {
// printf("// error ep %f\n", ep);
rec.error = 3;
satrec.error = 3;
// sgp4fix add return
return [false, false];
}
}

// -------------------- long period periodics ------------------
if (rec.method === 'd') {
if (satrec.method === 'd') {
sinip = Math.sin(xincp);
cosip = Math.cos(xincp);
rec.aycof = -0.5 * j3oj2 * sinip;
satrec.aycof = -0.5 * j3oj2 * sinip;

// sgp4fix for divide by zero for xincp = 180 deg
if (Math.abs(cosip + 1.0) > 1.5e-12) {
rec.xlcof = (-0.25 * j3oj2 * sinip * (3.0 + (5.0 * cosip))) / (1.0 + cosip);
satrec.xlcof = (-0.25 * j3oj2 * sinip * (3.0 + (5.0 * cosip))) / (1.0 + cosip);
} else {
rec.xlcof = (-0.25 * j3oj2 * sinip * (3.0 + (5.0 * cosip))) / temp4;
satrec.xlcof = (-0.25 * j3oj2 * sinip * (3.0 + (5.0 * cosip))) / temp4;
}
}

const axnl = ep * Math.cos(argpp);
temp = 1.0 / (am * (1.0 - (ep * ep)));
const aynl = (ep * Math.sin(argpp)) + (temp * rec.aycof);
const xl = mp + argpp + nodep + (temp * rec.xlcof * axnl);
const aynl = (ep * Math.sin(argpp)) + (temp * satrec.aycof);
const xl = mp + argpp + nodep + (temp * satrec.xlcof * axnl);

// --------------------- solve kepler's equation ---------------
const u = (xl - nodep) % twoPi;
Expand Down Expand Up @@ -354,7 +354,7 @@ export default function sgp4(satrec, tsince) {
const pl = am * (1.0 - el2);
if (pl < 0.0) {
// printf("// error pl %f\n", pl);
rec.error = 4;
satrec.error = 4;
// sgp4fix add return
return [false, false];
}
Expand All @@ -374,20 +374,20 @@ export default function sgp4(satrec, tsince) {
const temp2 = temp1 * temp;

// -------------- update for short period periodics ------------
if (rec.method === 'd') {
if (satrec.method === 'd') {
cosisq = cosip * cosip;
rec.con41 = (3.0 * cosisq) - 1.0;
rec.x1mth2 = 1.0 - cosisq;
rec.x7thm1 = (7.0 * cosisq) - 1.0;
satrec.con41 = (3.0 * cosisq) - 1.0;
satrec.x1mth2 = 1.0 - cosisq;
satrec.x7thm1 = (7.0 * cosisq) - 1.0;
}

const mrt = (rl * (1.0 - (1.5 * temp2 * betal * rec.con41))) +
(0.5 * temp1 * rec.x1mth2 * cos2u);
su -= 0.25 * temp2 * rec.x7thm1 * sin2u;
const mrt = (rl * (1.0 - (1.5 * temp2 * betal * satrec.con41))) +
(0.5 * temp1 * satrec.x1mth2 * cos2u);
su -= 0.25 * temp2 * satrec.x7thm1 * sin2u;
const xnode = nodep + (1.5 * temp2 * cosip * sin2u);
const xinc = xincp + (1.5 * temp2 * cosip * sinip * cos2u);
const mvt = rdotl - ((nm * temp1 * rec.x1mth2 * sin2u) / xke);
const rvdot = rvdotl + ((nm * temp1 * ((rec.x1mth2 * cos2u) + (1.5 * rec.con41))) / xke);
const mvt = rdotl - ((nm * temp1 * satrec.x1mth2 * sin2u) / xke);
const rvdot = rvdotl + ((nm * temp1 * ((satrec.x1mth2 * cos2u) + (1.5 * satrec.con41))) / xke);

// --------------------- orientation vectors -------------------
const sinsu = Math.sin(su);
Expand Down Expand Up @@ -420,17 +420,17 @@ export default function sgp4(satrec, tsince) {
// sgp4fix for decaying satellites
if (mrt < 1.0) {
// printf("// decay condition %11.6f \n",mrt);
rec.error = 6;
satrec.error = 6;
return {
position: false,
velocity: false,
satrec: rec,
};
}

return {
position: r,
velocity: v,
satrec: rec,
};

/* eslint-enable no-param-reassign */
}

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