v_vector.h

Go to the documentation of this file.

    1 /*=========================================================================
    2   Original version -- Copyright (c) 2006 Sandia Corporation.
    3   All rights reserved.
    4   See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
    5  
    6      This software is distributed WITHOUT ANY WARRANTY; without even
    7      the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
    8      PURPOSE.  See the above copyright notice for more information.
    9  
   10 =========================================================================*/
   11  
   12 #ifndef VERDICT_VECTOR
   13 #define VERDICT_VECTOR
   14  
   15 #include "moab/verdict.h"
   16 #include <cmath>
   17 #include <cassert>
   18  
   19 // computes the dot product of 3d vectors
   20 inline double dot_product( double vec1[], double vec2[] )
   21 {
   22     double answer = vec1[0] * vec2[0] + vec1[1] * vec2[1] + vec1[2] * vec2[2];
   23     return answer;
   24 }
   25  
   26 // normalize a vector
   27 inline void normalize( double vec[] )
   28 {
   29     double x = sqrt( vec[0] * vec[0] + vec[1] * vec[1] + vec[2] * vec[2] );
   30  
   31     vec[0] /= x;
   32     vec[1] /= x;
   33     vec[2] /= x;
   34 }
   35  
   36 // computes the cross product
   37 inline double* cross_product( double vec1[], double vec2[], double answer[] )
   38 {
   39     answer[0] = vec1[1] * vec2[2] - vec1[2] * vec2[1];
   40     answer[1] = vec1[2] * vec2[0] - vec1[0] * vec2[2];
   41     answer[2] = vec1[0] * vec2[1] - vec1[1] * vec2[0];
   42     return answer;
   43 }
   44  
   45 // computes the length of a vector
   46 inline double length( double vec[] )
   47 {
   48     return sqrt( vec[0] * vec[0] + vec[1] * vec[1] + vec[2] * vec[2] );
   49 }
   50  
   51 // computes the square length of a vector
   52 inline double length_squared( double vec[] )
   53 {
   54     return ( vec[0] * vec[0] + vec[1] * vec[1] + vec[2] * vec[2] );
   55 }
   56  
   57 // computes the interior angle between 2 vectors in degrees
   58 inline double interior_angle( double vec1[], double vec2[] )
   59 {
   60     double cosAngle, angleRad;
   61     double length1 = length( vec1 );
   62     double length2 = length( vec2 );
   63     assert( ( length1 > 0.0 && length2 > 0.0 ) );
   64  
   65     cosAngle = dot_product( vec1, vec2 ) / ( length1 * length2 );
   66  
   67     if( ( cosAngle > 1.0 ) && ( cosAngle < 1.0001 ) )
   68     {
   69         cosAngle = 1.0;
   70     }
   71     else if( cosAngle < -1.0 && cosAngle > -1.0001 )
   72     {
   73         cosAngle = -1.0;
   74     }
   75     else
   76     {
   77         assert( cosAngle < 1.0001 && cosAngle > -1.0001 );
   78     }
   79  
   80     angleRad = acos( cosAngle );
   81     return ( ( angleRad * 180. ) / VERDICT_PI );
   82 }
   83  
   84 #endif