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Extend precession test with a second epoch one second later #4863

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Extend precession test with a second epoch one second later #4863

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Extend precession test with a second epoch one second later
IsseiHasegawa Apr 8, 2026
372044e
Remove unused includes from testPrecession.cpp
IsseiHasegawa Apr 8, 2026
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34 changes: 29 additions & 5 deletions src/tests/testPrecession.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -17,10 +17,6 @@
* Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA.
*/

#include <QObject>
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@gzotti gzotti Apr 8, 2026

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These includes were probably used by code now only commented away, and will be needed when taking up development in case any doubts in the precession model appear.

#include <QtDebug>
#include <QVariantList>

#include "tests/testPrecession.hpp"
#include "StelUtils.hpp"
#include "VecMath.hpp"
Expand Down Expand Up @@ -116,5 +112,33 @@ void TestPrecession::testPrecessionAnglesVondrak()
// according to Fig12 in the paper, a few arcseconds of difference between PQXY and Capitaine parametrisation are allowed.
QVERIFY2((angleCap-angleRef)*3600.0<6.0, QString("Angle between rotation matrices too different!").toUtf8());

//TODO: Add more dates and verify this angle difference is limited to what we can see in Fig.12
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@gzotti gzotti Apr 8, 2026

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Adding the same dates plus one second IMO does not qualify to remove the intent of the TODO message. Adding a few centuries might do it, but we have no "official" reference values.

// Same construction one second later: no tabulated paper vectors here, only matrix/angle agreement.
const double JulianDay2 = JulianDay + 1.0 / 86400.0;
getPrecessionAnglesVondrak(JulianDay2, &epsilon_A, &chi_A, &omega_A, &psi_A);
getPrecessionAnglesVondrakPQXYe(-1234.567, &P_A, &Q_A, &X_A, &Y_A, &epsilon_A);
getPrecessionAnglesVondrakPQXYe(JulianDay2, &P_A, &Q_A, &X_A, &Y_A, &epsilon_A);
Z = sqrt(qMax(1.0 - P_A * P_A - Q_A * Q_A, 0.0));
W = X_A * X_A + Y_A * Y_A;
VEC2 = -Q_A * C - Z * S;
VEC3 = -Q_A * S + Z * C;
VEQ3 = (W < 1.0 ? sqrt(1.0 - W) : 0.0);
PECL = Vec3d(P_A, VEC2, VEC3);
PEQR = Vec3d(X_A, Y_A, VEQ3);
EQX = PEQR ^ PECL;
EQX.normalize();
V = PEQR ^ EQX;
RP = Mat3d(EQX[0], EQX[1], EQX[2], V[0], V[1], V[2], PEQR[0], PEQR[1], PEQR[2]);
RRot = Mat4d::xrotation(eps0) * Mat4d::zrotation(-psi_A) * Mat4d::xrotation(-omega_A) * Mat4d::zrotation(chi_A);
RP4 = Mat4d(EQX[0], EQX[1], EQX[2], 0, V[0], V[1], V[2], 0, PEQR[0], PEQR[1], PEQR[2], 0, 0, 0, 0, 1);
matDiff3x3 = (RRot - RP4).upper3x3();
max = 0.0;
for (int i = 0; i < 9; ++i)
{
if (fabs(matDiff3x3[i]) > max)
max = fabs(matDiff3x3[i]);
}
QVERIFY2(max < 2e-5, QString("JD %1: precession matrices differ by too much.").arg(JulianDay2).toUtf8());
angleRef = RP.angle() * 180.0 / M_PI;
angleCap = RRot.upper3x3().angle() * 180.0 / M_PI;
QVERIFY2((angleCap - angleRef) * 3600.0 < 6.0, QString("JD %1: angle between rotation matrices too different!").arg(JulianDay2).toUtf8());
}
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