#include "sofa.h"
void iauPv2s(double pv[2][3],
double *theta, double *phi, double *r,
double *td, double *pd, double *rd)
/*
** - - - - - - - -
** i a u P v 2 s
** - - - - - - - -
**
** Convert position/velocity from Cartesian to spherical coordinates.
**
** This function is part of the International Astronomical Union's
** SOFA (Standards Of Fundamental Astronomy) software collection.
**
** Status: vector/matrix support function.
**
** Given:
** pv double[2][3] pv-vector
**
** Returned:
** theta double longitude angle (radians)
** phi double latitude angle (radians)
** r double radial distance
** td double rate of change of theta
** pd double rate of change of phi
** rd double rate of change of r
**
** Notes:
**
** 1) If the position part of pv is null, theta, phi, td and pd
** are indeterminate. This is handled by extrapolating the
** position through unit time by using the velocity part of
** pv. This moves the origin without changing the direction
** of the velocity component. If the position and velocity
** components of pv are both null, zeroes are returned for all
** six results.
**
** 2) If the position is a pole, theta, td and pd are indeterminate.
** In such cases zeroes are returned for all three.
**
** This revision: 2021 May 11
**
** SOFA release 2021-05-12
**
** Copyright (C) 2021 IAU SOFA Board. See notes at end.
*/
{
double x, y, z, xd, yd, zd, rxy2, rxy, r2, rtrue, rw, xyp;
/* Components of position/velocity vector. */
x = pv[0][0];
y = pv[0][1];
z = pv[0][2];
xd = pv[1][0];
yd = pv[1][1];
zd = pv[1][2];
/* Component of r in XY plane squared. */
rxy2 = x*x + y*y;
/* Modulus squared. */
r2 = rxy2 + z*z;
/* Modulus. */
rtrue = sqrt(r2);
/* If null vector, move the origin along the direction of movement. */
rw = rtrue;
if (rtrue == 0.0) {
x = xd;
y = yd;
z = zd;
rxy2 = x*x + y*y;
r2 = rxy2 + z*z;
rw = sqrt(r2);
}
/* Position and velocity in spherical coordinates. */
rxy = sqrt(rxy2);
xyp = x*xd + y*yd;
if (rxy2 != 0.0) {
*theta = atan2(y, x);
*phi = atan2(z, rxy);
*td = (x*yd - y*xd) / rxy2;
*pd = (zd*rxy2 - z*xyp) / (r2*rxy);
} else {
*theta = 0.0;
*phi = (z != 0.0) ? atan2(z, rxy) : 0.0;
*td = 0.0;
*pd = 0.0;
}
*r = rtrue;
*rd = (rw != 0.0) ? (xyp + z*zd) / rw : 0.0;
/* Finished. */
/*----------------------------------------------------------------------
**
** Copyright (C) 2021
** Standards Of Fundamental Astronomy Board
** of the International Astronomical Union.
**
** =====================
** SOFA Software License
** =====================
**
** NOTICE TO USER:
**
** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND
** CONDITIONS WHICH APPLY TO ITS USE.
**
** 1. The Software is owned by the IAU SOFA Board ("SOFA").
**
** 2. Permission is granted to anyone to use the SOFA software for any
** purpose, including commercial applications, free of charge and
** without payment of royalties, subject to the conditions and
** restrictions listed below.
**
** 3. You (the user) may copy and distribute SOFA source code to others,
** and use and adapt its code and algorithms in your own software,
** on a world-wide, royalty-free basis. That portion of your
** distribution that does not consist of intact and unchanged copies
** of SOFA source code files is a "derived work" that must comply
** with the following requirements:
**
** a) Your work shall be marked or carry a statement that it
** (i) uses routines and computations derived by you from
** software provided by SOFA under license to you; and
** (ii) does not itself constitute software provided by and/or
** endorsed by SOFA.
**
** b) The source code of your derived work must contain descriptions
** of how the derived work is based upon, contains and/or differs
** from the original SOFA software.
**
** c) The names of all routines in your derived work shall not
** include the prefix "iau" or "sofa" or trivial modifications
** thereof such as changes of case.
**
** d) The origin of the SOFA components of your derived work must
** not be misrepresented; you must not claim that you wrote the
** original software, nor file a patent application for SOFA
** software or algorithms embedded in the SOFA software.
**
** e) These requirements must be reproduced intact in any source
** distribution and shall apply to anyone to whom you have
** granted a further right to modify the source code of your
** derived work.
**
** Note that, as originally distributed, the SOFA software is
** intended to be a definitive implementation of the IAU standards,
** and consequently third-party modifications are discouraged. All
** variations, no matter how minor, must be explicitly marked as
** such, as explained above.
**
** 4. You shall not cause the SOFA software to be brought into
** disrepute, either by misuse, or use for inappropriate tasks, or
** by inappropriate modification.
**
** 5. The SOFA software is provided "as is" and SOFA makes no warranty
** as to its use or performance. SOFA does not and cannot warrant
** the performance or results which the user may obtain by using the
** SOFA software. SOFA makes no warranties, express or implied, as
** to non-infringement of third party rights, merchantability, or
** fitness for any particular purpose. In no event will SOFA be
** liable to the user for any consequential, incidental, or special
** damages, including any lost profits or lost savings, even if a
** SOFA representative has been advised of such damages, or for any
** claim by any third party.
**
** 6. The provision of any version of the SOFA software under the terms
** and conditions specified herein does not imply that future
** versions will also be made available under the same terms and
** conditions.
*
** In any published work or commercial product which uses the SOFA
** software directly, acknowledgement (see www.iausofa.org) is
** appreciated.
**
** Correspondence concerning SOFA software should be addressed as
** follows:
**
** By email: sofa@ukho.gov.uk
** By post: IAU SOFA Center
** HM Nautical Almanac Office
** UK Hydrographic Office
** Admiralty Way, Taunton
** Somerset, TA1 2DN
** United Kingdom
**
**--------------------------------------------------------------------*/
}