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#include "erfa.h"
void eraPv2s(double pv[2][3],
double *theta, double *phi, double *r,
double *td, double *pd, double *rd)
/*
** - - - - - - - -
** e r a P v 2 s
** - - - - - - - -
**
** Convert position/velocity from Cartesian to spherical coordinates.
**
** 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
**
** Copyright (C) 2013-2021, NumFOCUS Foundation.
** Derived, with permission, from the SOFA library. See notes at end of file.
*/
{
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) 2013-2021, NumFOCUS Foundation.
** All rights reserved.
**
** This library is derived, with permission, from the International
** Astronomical Union's "Standards of Fundamental Astronomy" library,
** available from http://www.iausofa.org.
**
** The ERFA version is intended to retain identical functionality to
** the SOFA library, but made distinct through different function and
** file names, as set out in the SOFA license conditions. The SOFA
** original has a role as a reference standard for the IAU and IERS,
** and consequently redistribution is permitted only in its unaltered
** state. The ERFA version is not subject to this restriction and
** therefore can be included in distributions which do not support the
** concept of "read only" software.
**
** Although the intent is to replicate the SOFA API (other than
** replacement of prefix names) and results (with the exception of
** bugs; any that are discovered will be fixed), SOFA is not
** responsible for any errors found in this version of the library.
**
** If you wish to acknowledge the SOFA heritage, please acknowledge
** that you are using a library derived from SOFA, rather than SOFA
** itself.
**
**
** TERMS AND CONDITIONS
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
**
** 1 Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
**
** 2 Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
**
** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
** the International Astronomical Union nor the names of its
** contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
** POSSIBILITY OF SUCH DAMAGE.
**
*/