.. _program_listing_file_src_t8_mat.h:

Program Listing for File t8_mat.h
=================================

|exhale_lsh| :ref:`Return to documentation for file <file_src_t8_mat.h>` (``src/t8_mat.h``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   /*
     This file is part of t8code.
     t8code is a C library to manage a collection (a forest) of multiple
     connected adaptive space-trees of general element classes in parallel.
   
     Copyright (C) 2023 the developers
   
     t8code is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; either version 2 of the License, or
     (at your option) any later version.
   
     t8code 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 General Public License for more details.
   
     You should have received a copy of the GNU General Public License
     along with t8code; if not, write to the Free Software Foundation, Inc.,
     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
   */
   
   #ifndef T8_MAT_H
   #define T8_MAT_H
   
   #include <math.h>
   
   static inline void
   t8_mat_init_xrot (double mat[3][3], const double angle)
   {
     /* first row */
     mat[0][0] = 1.0;
     mat[0][1] = 0.0;
     mat[0][2] = 0.0;
   
     /* second row */
     mat[1][0] = 0.0;
     mat[1][1] = cos (angle);
     mat[1][2] = -sin (angle);
   
     /* third row */
     mat[2][0] = 0.0;
     mat[2][1] = sin (angle);
     mat[2][2] = cos (angle);
   }
   
   static inline void
   t8_mat_init_yrot (double mat[3][3], const double angle)
   {
     /* first row */
     mat[0][0] = cos (angle);
     mat[0][1] = 0.0;
     mat[0][2] = sin (angle);
   
     /* second row */
     mat[1][0] = 0.0;
     mat[1][1] = 1.0;
     mat[1][2] = 0.0;
   
     /* third row */
     mat[2][0] = -sin (angle);
     mat[2][1] = 0.0;
     mat[2][2] = cos (angle);
   }
   
   static inline void
   t8_mat_init_zrot (double mat[3][3], const double angle)
   {
     /* first row */
     mat[0][0] = cos (angle);
     mat[0][1] = -sin (angle);
     mat[0][2] = 0.0;
   
     /* second row */
     mat[1][0] = sin (angle);
     mat[1][1] = cos (angle);
     mat[1][2] = 0.0;
   
     /* third row */
     mat[2][0] = 0.0;
     mat[2][1] = 0.0;
     mat[2][2] = 1.0;
   }
   
   static inline void
   t8_mat_mult_vec (const double mat[3][3], const double a[3], double b[3])
   {
     b[0] = mat[0][0] * a[0] + mat[0][1] * a[1] + mat[0][2] * a[2];
     b[1] = mat[1][0] * a[0] + mat[1][1] * a[1] + mat[1][2] * a[2];
     b[2] = mat[2][0] * a[0] + mat[2][1] * a[1] + mat[2][2] * a[2];
   }
   
   static inline void
   t8_mat_mult_mat (const double A[3][3], const double B[3][3], double C[3][3])
   {
     for (int i = 0; i < 3; i++) {
       for (int j = 0; j < 3; j++) {
         C[i][j] = 0.0;
       }
     }
   
     for (int i = 0; i < 3; i++) {
       for (int j = 0; j < 3; j++) {
         for (int k = 0; k < 3; k++) {
           C[i][j] = C[i][j] + A[i][k] * B[k][j];
         }
       }
     }
   }
   
   #endif /* !T8_MAT_H */