v_vector.h

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/*=========================================================================
 Original version -- Copyright (c) 2006 Sandia Corporation.
 All rights reserved.
 See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
 
 This software is distributed WITHOUT ANY WARRANTY; without even
 the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 PURPOSE. See the above copyright notice for more information.
 
=========================================================================*/
 
#ifndef VERDICT_VECTOR
#define VERDICT_VECTOR
 
#include "moab/verdict.h"
#include <cmath>
#include <cassert>
 
// computes the dot product of 3d vectors
inline double dot_product( double vec1[], double vec2[] )
{
 double answer = vec1[0] * vec2[0] + vec1[1] * vec2[1] + vec1[2] * vec2[2];
 return answer;
}
 
// normalize a vector
inline void normalize( double vec[] )
{
 double x = sqrt( vec[0] * vec[0] + vec[1] * vec[1] + vec[2] * vec[2] );
 
 vec[0] /= x;
 vec[1] /= x;
 vec[2] /= x;
}
 
// computes the cross product
inline double* cross_product( double vec1[], double vec2[], double answer[] )
{
 answer[0] = vec1[1] * vec2[2] - vec1[2] * vec2[1];
 answer[1] = vec1[2] * vec2[0] - vec1[0] * vec2[2];
 answer[2] = vec1[0] * vec2[1] - vec1[1] * vec2[0];
 return answer;
}
 
// computes the length of a vector
inline double length( double vec[] )
{
 return sqrt( vec[0] * vec[0] + vec[1] * vec[1] + vec[2] * vec[2] );
}
 
// computes the square length of a vector
inline double length_squared( double vec[] )
{
 return ( vec[0] * vec[0] + vec[1] * vec[1] + vec[2] * vec[2] );
}
 
// computes the interior angle between 2 vectors in degrees
inline double interior_angle( double vec1[], double vec2[] )
{
 double cosAngle, angleRad;
 double length1 = length( vec1 );
 double length2 = length( vec2 );
 assert( ( length1 > 0.0 && length2 > 0.0 ) );
 
 cosAngle = dot_product( vec1, vec2 ) / ( length1 * length2 );
 
 if( ( cosAngle > 1.0 ) && ( cosAngle < 1.0001 ) )
 {
 cosAngle = 1.0;
 }
 else if( cosAngle < -1.0 && cosAngle > -1.0001 )
 {
 cosAngle = -1.0;
 }
 else
 {
 assert( cosAngle < 1.0001 && cosAngle > -1.0001 );
 }
 
 angleRad = acos( cosAngle );
 return ( ( angleRad * 180. ) / VERDICT_PI );
}
 
#endif