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+#include "erfa.h"
+
+void eraRx(double phi, double r[3][3])
+/*
+** - - - - - -
+** e r a R x
+** - - - - - -
+**
+** Rotate an r-matrix about the x-axis.
+**
+** Given:
+** phi double angle (radians)
+**
+** Given and returned:
+** r double[3][3] r-matrix, rotated
+**
+** Notes:
+**
+** 1) Calling this function with positive phi incorporates in the
+** supplied r-matrix r an additional rotation, about the x-axis,
+** anticlockwise as seen looking towards the origin from positive x.
+**
+** 2) The additional rotation can be represented by this matrix:
+**
+** ( 1 0 0 )
+** ( )
+** ( 0 + cos(phi) + sin(phi) )
+** ( )
+** ( 0 - sin(phi) + cos(phi) )
+**
+** Copyright (C) 2013-2016, NumFOCUS Foundation.
+** Derived, with permission, from the SOFA library. See notes at end of file.
+*/
+{
+ double s, c, a10, a11, a12, a20, a21, a22;
+
+
+ s = sin(phi);
+ c = cos(phi);
+
+ a10 = c*r[1][0] + s*r[2][0];
+ a11 = c*r[1][1] + s*r[2][1];
+ a12 = c*r[1][2] + s*r[2][2];
+ a20 = - s*r[1][0] + c*r[2][0];
+ a21 = - s*r[1][1] + c*r[2][1];
+ a22 = - s*r[1][2] + c*r[2][2];
+
+ r[1][0] = a10;
+ r[1][1] = a11;
+ r[1][2] = a12;
+ r[2][0] = a20;
+ r[2][1] = a21;
+ r[2][2] = a22;
+
+ return;
+
+}
+/*----------------------------------------------------------------------
+**
+**
+** Copyright (C) 2013-2016, 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.
+**
+*/