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/*============================================================================
WCSLIB 7.12 - an implementation of the FITS WCS standard.
Copyright (C) 1995-2022, Mark Calabretta
This file is part of WCSLIB.
WCSLIB is free software: you can redistribute it and/or modify it under the
terms of the GNU Lesser General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your option)
any later version.
WCSLIB is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
more details.
You should have received a copy of the GNU Lesser General Public License
along with WCSLIB. If not, see http://www.gnu.org/licenses.
Author: Mark Calabretta, Australia Telescope National Facility, CSIRO.
http://www.atnf.csiro.au/people/Mark.Calabretta
$Id: tsph.c,v 7.12 2022/09/09 04:57:58 mcalabre Exp $
*=============================================================================
*
* tsph tests the spherical coordinate transformation routines for closure.
*
*---------------------------------------------------------------------------*/
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include <sph.h>
#include <wcstrig.h>
int main()
{
int j, k, lat, lng, nFail = 0;
double cel1[181][2], cel2[181][2], coslat, dlat, dlatmx, dlng, dlngmx,
eul[5], lng1[361], lng2[361], lat1, lat2[361], ntv[181][2], phi[361],
theta[361], zeta;
const double tol = 1.0e-12;
printf(
"Testing closure of WCSLIB coordinate transformation routines (tsph.c)\n"
"---------------------------------------------------------------------\n");
printf ("Reporting tolerance:%8.1e degrees of arc.\n", tol);
dlngmx = 0.0;
dlatmx = 0.0;
for (k = 0; k < 3; k++) {
// Set reference angles.
eul[0] = 90.0;
eul[2] = -90.0;
if (k < 2) {
// Special-case transformations.
eul[1] = (k==0) ? 0.0 : 180.0;
} else {
eul[1] = 30.0;
}
printf("\n%s\n%s%10.4f%10.4f%10.4f\n",
"Celestial longitude and latitude of the native pole, and native",
"longitude of the celestial pole (degrees):", eul[0], eul[1], eul[2]);
eul[3] = cosd(eul[1]);
eul[4] = sind(eul[1]);
// Test points at constant latitude.
for (lat = 90; lat >= -90; lat--) {
lat1 = (double)lat;
coslat = cosd(lat1);
for (j = 0, lng = -180; lng <= 180; lng++, j++) {
lng1[j] = (double)lng;
}
sphs2x(eul, 361, 1, 1, 1, lng1, &lat1, phi, theta);
sphx2s(eul, 361, 0, 1, 1, phi, theta, lng2, lat2);
// Exact results are expected for special-case transformations.
if (k == 0) {
// Identity transformation.
for (j = 0; j <= 360; j++) {
if (phi[j] != lng1[j] || theta[j] != lat1) {
nFail++;
printf(" Error: lng1 =%20.15f lat1 =%20.15f\n",
lng1[j], lat1);
printf(" phi =%20.15f theta =%20.15f\n",
phi[j], theta[j]);
}
}
} else if (k == 1) {
// Antipodal transformation.
for (j = 0; j <= 360; j++) {
if (phi[j] != -lng1[j] || theta[j] != -lat1) {
nFail++;
printf(" Error: lng1 =%20.15f lat1 =%20.15f\n",
lng1[j], lat1);
printf(" phi =%20.15f theta =%20.15f\n",
phi[j], theta[j]);
}
}
}
// Do another round trip, just for good measure.
sphs2x(eul, 361, 0, 1, 1, lng2, lat2, phi, theta);
sphx2s(eul, 361, 0, 1, 1, phi, theta, lng2, lat2);
// Check closure.
for (j = 0; j <= 360; j++) {
dlng = fabs(lng2[j] - lng1[j]);
if (dlng > 180.0) dlng = fabs(dlng-360.0);
dlng *= coslat;
dlat = fabs(lat2[j] - lat1);
if (dlng > dlngmx) dlngmx = dlng;
if (dlat > dlatmx) dlatmx = dlat;
if (dlng > tol || dlat > tol) {
nFail++;
printf("Unclosed: lng1 =%20.15f lat1 =%20.15f\n", lng1[j], lat1);
printf(" phi =%20.15f theta =%20.15f\n", phi[j], theta[j]);
printf(" lng2 =%20.15f lat2 =%20.15f\n", lng2[j], lat2[j]);
}
}
}
// Test vector strides using points in spirals from south to north.
for (lng = 0; lng <= 360; lng++) {
for (j = 0, lat = -90; lat <= 90; j++, lat++) {
cel1[j][0] = (double)((lng+j)%360 - 180);
cel1[j][1] = (double)lat;
}
sphs2x(eul, 181, 0, 2, 2, &(cel1[0][0]), &(cel1[0][1]),
&(ntv[0][0]), &(ntv[0][1]));
sphx2s(eul, 181, 0, 2, 2, &(ntv[0][0]), &(ntv[0][1]),
&(cel2[0][0]), &(cel2[0][1]));
// Exact results are expected for special-case transformations.
if (k == 0) {
// Identity transformation.
for (j = 0; j <= 180; j++) {
if (ntv[j][0] != cel1[j][0] || ntv[j][1] != cel1[j][1]) {
nFail++;
printf(" Error: lng1 =%20.15f lat1 =%20.15f\n",
cel1[j][0], cel1[j][1]);
printf(" phi =%20.15f theta =%20.15f\n",
ntv[j][0], ntv[j][1]);
}
}
} else if (k == 1) {
// Antipodal transformation.
for (j = 0; j <= 180; j++) {
if (ntv[j][0] != -cel1[j][0] || ntv[j][1] != -cel1[j][1]) {
nFail++;
printf(" Error: lng1 =%20.15f lat1 =%20.15f\n",
cel1[j][0], cel1[j][1]);
printf(" phi =%20.15f theta =%20.15f\n",
ntv[j][0], ntv[j][1]);
}
}
}
// Check closure.
for (j = 0; j <= 180; j++) {
dlng = fabs(cel2[j][0] - cel1[j][0]);
if (dlng > 180.0) dlng = fabs(dlng - 360.0);
dlng *= cosd(cel1[j][1]);
dlat = fabs(cel2[j][1] - cel1[j][1]);
if (dlng > dlngmx) dlngmx = dlng;
if (dlat > dlatmx) dlatmx = dlat;
if (dlng > tol || dlat > tol) {
nFail++;
printf("Unclosed: lng1 =%20.15f lat1 =%20.15f\n",
cel1[j][0], cel1[j][1]);
printf(" phi =%20.15f theta =%20.15f\n",
ntv[j][0], ntv[j][1]);
printf(" lng2 =%20.15f lat2 =%20.15f\n",
cel2[j][0], cel2[j][1]);
}
}
}
}
// Test closure at points close to the pole.
for (j = -1; j <= 1; j += 2) {
zeta = 1.0;
lng1[0] = -180.0;
for (lat = 0; lat < 12; lat++) {
lat1 = (double)j*(90.0 - zeta);
sphs2x(eul, 1, 1, 1, 1, lng1, &lat1, phi, theta);
sphx2s(eul, 1, 1, 1, 1, phi, theta, lng2, lat2);
dlng = fabs(lng2[0] - lng1[0]);
if (dlng > 180.0) dlng = fabs(dlng - 360.0);
dlng *= coslat;
dlat = fabs(lat2[0] - lat1);
if (dlng > dlngmx) dlngmx = dlng;
if (dlat > dlatmx) dlatmx = dlat;
if (dlng > tol || dlat > tol) {
nFail++;
printf("Unclosed: lng1 =%20.15f lat1 =%20.15f\n", lng1[0], lat1);
printf(" phi =%20.15f theta =%20.15f\n", phi[0], theta[0]);
printf(" lng2 =%20.15f lat2 =%20.15f\n", lng2[0], lat2[0]);
}
zeta /= 10.0;
lng1[0] += 30.0;
}
}
printf("\nsphs2x/sphx2s: Maximum closure residual = %.1e (lng), %.1e (lat) "
"deg.\n", dlngmx, dlatmx);
if (nFail) {
printf("\nFAIL: %d closure residuals exceed reporting tolerance.\n",
nFail);
} else {
printf("\nPASS: All closure residuals are within reporting tolerance.\n");
}
return nFail;
}
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