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70 lines
1.8 KiB
Fortran
70 lines
1.8 KiB
Fortran
SUBROUTINE sla_DCC2S (V, A, B)
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*+
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* - - - - - -
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* D C C 2 S
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* - - - - - -
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*
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* Cartesian to spherical coordinates (double precision)
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*
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* Given:
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* V d(3) x,y,z vector
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*
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* Returned:
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* A,B d spherical coordinates in radians
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*
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* The spherical coordinates are longitude (+ve anticlockwise looking
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* from the +ve latitude pole) and latitude. The Cartesian coordinates
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* are right handed, with the x axis at zero longitude and latitude, and
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* the z axis at the +ve latitude pole.
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*
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* If V is null, zero A and B are returned. At either pole, zero A is
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* returned.
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*
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* Last revision: 22 July 2004
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*
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* Copyright P.T.Wallace. All rights reserved.
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*
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* License:
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program (see SLA_CONDITIONS); if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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* Boston, MA 02111-1307 USA
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*
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*-
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IMPLICIT NONE
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DOUBLE PRECISION V(3),A,B
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DOUBLE PRECISION X,Y,Z,R
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X = V(1)
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Y = V(2)
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Z = V(3)
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R = SQRT(X*X+Y*Y)
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IF (R.EQ.0D0) THEN
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A = 0D0
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ELSE
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A = ATAN2(Y,X)
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END IF
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IF (Z.EQ.0D0) THEN
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B = 0D0
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ELSE
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B = ATAN2(Z,R)
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END IF
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END
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