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*=======================================================================
*
* WCSLIB 8.5 - an implementation of the FITS WCS standard.
* Copyright (C) 1995-2025, 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.f,v 8.5 2025/12/06 13:47:41 mcalabre Exp $
*=======================================================================
PROGRAM TSPH
*-----------------------------------------------------------------------
*
* TSPH tests the forward and reverse spherical coordinate transformation
* routines for closure.
*
*-----------------------------------------------------------------------
INTEGER J, LAT, LNG, NFAIL, SPHS2X, SPHX2S, STATUS
DOUBLE PRECISION COSLAT, DLAT, DLATMX, DLNG, DLNGMX, LNG1(361),
: LNG2(361), EUL(5), LAT1, LAT2(361), PHI(361),
: THETA(361), TOL, ZETA
PARAMETER (TOL = 1D-12)
DOUBLE PRECISION D2R, PI
PARAMETER (PI = 3.141592653589793238462643D0)
PARAMETER (D2R = PI/180D0)
*-----------------------------------------------------------------------
WRITE (*, 10)
10 FORMAT ('Testing closure of WCSLIB coordinate transformation ',
: 'routines (tsph.f)',/,
: '----------------------------------------------------',
: '-----------------')
* Set reference angles.
EUL(1) = 90D0
EUL(2) = 30D0
EUL(3) = -90D0
WRITE (*, 20) (EUL(J),J=1,3)
20 FORMAT (/,'Celestial longitude and latitude of the native pole, ',
: 'and native',/,'longitude of the celestial pole ',
: '(degrees):',3F10.4)
EUL(4) = COS(EUL(2)*D2R)
EUL(5) = SIN(EUL(2)*D2R)
WRITE (*, 30) TOL
30 FORMAT ('Reporting tolerance:',1PG8.1,' degrees of arc.')
NFAIL = 0
DLNGMX = 0D0
DLATMX = 0D0
DO 70 LAT = 90, -90, -1
LAT1 = DBLE(LAT)
COSLAT = COS(LAT1*D2R)
J = 1
DO 40 LNG = -180, 180
LNG1(J) = DBLE(LNG)
J = J + 1
40 CONTINUE
STATUS = SPHS2X (EUL, 361, 1, 1, 1, LNG1, LAT1, PHI, THETA)
STATUS = SPHX2S (EUL, 361, 0, 1, 1, PHI, THETA, LNG2, LAT2)
DO 60 J = 1, 361
DLNG = ABS(LNG2(J) - LNG1(J))
IF (DLNG.GT.180D0) DLNG = ABS(DLNG-360D0)
DLNG = DLNG*COSLAT
DLAT = ABS(LAT2(J)-LAT1)
IF (DLNG.GT.DLNGMX) DLNGMX = DLNG
IF (DLAT.GT.DLATMX) DLATMX = DLAT
IF (DLNG.GT.TOL .OR. DLAT.GT.TOL) THEN
NFAIL = NFAIL + 1
WRITE (*, 50) LNG1(J), LAT1, PHI(J), THETA(J), LNG2(J),
: LAT2(J)
50 FORMAT ('Unclosed: LNG1 =',F20.15,' LAT1 =',F20.15,/,
: ' PHI =',F20.15,' THETA =',F20.15,/,
: ' LNG2 =',F20.15,' LAT2 =',F20.15)
END IF
60 CONTINUE
70 CONTINUE
* Test closure at points close to the pole.
DO 90 J = -1, 1, 2
ZETA = 1D0
LNG1(1) = -180D0
DO 80 LAT = 1, 12
LAT1 = DBLE(J)*(90D0 - ZETA)
STATUS = SPHS2X (EUL, 1, 1, 1, 1, LNG1, LAT1, PHI, THETA)
STATUS = SPHX2S (EUL, 1, 1, 1, 1, PHI, THETA, LNG2, LAT2)
DLNG = ABS(LNG2(1) - LNG1(1))
IF (DLNG.GT.180D0) DLNG = ABS(DLNG-360D0)
DLNG = DLNG*COSLAT
DLAT = ABS(LAT2(1)-LAT1)
IF (DLNG.GT.DLNGMX) DLNGMX = DLNG
IF (DLAT.GT.DLATMX) DLATMX = DLAT
IF (DLNG.GT.TOL .OR. DLAT.GT.TOL) THEN
NFAIL = NFAIL + 1
WRITE (*, 50) LNG1(1), LAT1, PHI(1), THETA(1), LNG2(1),
: LAT2(1)
END IF
ZETA = ZETA/10D0
LNG1(1) = LNG1(1) + 30D0
80 CONTINUE
90 CONTINUE
WRITE (*, 100) DLNGMX, DLATMX
100 FORMAT (/,'SPHS2X/SPHX2S: Maximum closure residual =',1P,E8.1,
: ' (lng)',E8.1,' (lat) deg.')
IF (NFAIL.NE.0) THEN
WRITE (*, 110) NFAIL
110 FORMAT (/,'FAIL:',I5,' closure residuals exceed reporting ',
: 'tolerance.')
ELSE
WRITE (*, 120)
120 FORMAT (/,'PASS: All closure residuals are within reporting ',
: 'tolerance.')
END IF
END
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