fn_intpoints_gauss_tet4.hpp

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/*
 * BELFEM -- The Berkeley Lab Finite Element Framework
 * Copyright (c) 2026, The Regents of the University of California,
 * through Lawrence Berkeley National Laboratory (subject to receipt of any required
 * approvals from the U.S. Dept. of Energy).  All rights reserved.
 *
 * Developers: Christian Messe, Gregory Giard
 *
 * See the top-level LICENSE file for the complete license and disclaimer.
 */
 
#ifndef BELFEM_FN_INTPOINTS_GAUSS_TET4_HPP
#define BELFEM_FN_INTPOINTS_GAUSS_TET4_HPP
 
#include "typedefs.hpp"
#include "cl_Vector.hpp"
#include "cl_Matrix.hpp"
 
namespace belfem
{
    namespace integration
    {
// ----------------------------------------------------------------------------
        inline void
        gauss_tet4(
                Vector <real> & aWeights,
                Matrix <real> & aPoints )
        {
            real tAlpha = ( 5.0 - std::sqrt( 5.0 ) )/20.0;
            real tBeta = 1.0 - 3.0*tAlpha;
 
            aPoints.set_size( 4, 4 );
 
            aPoints( 0, 0 ) = tBeta;
            aPoints( 1, 0 ) = tAlpha;
            aPoints( 2, 0 ) = tAlpha;
            aPoints( 3, 0 ) = tAlpha;
 
            aPoints( 0, 1 ) = tAlpha;
            aPoints( 1, 1 ) = tBeta;
            aPoints( 2, 1 ) = tAlpha;
            aPoints( 3, 1 ) = tAlpha;
 
            aPoints( 0, 2 ) = tAlpha;
            aPoints( 1, 2 ) = tAlpha;
            aPoints( 2, 2 ) = tBeta;
            aPoints( 3, 2 ) = tAlpha;
 
            aPoints( 0, 3 ) = tAlpha;
            aPoints( 1, 3 ) = tAlpha;
            aPoints( 2, 3 ) = tAlpha;
            aPoints( 3, 3 ) = tBeta;
 
            aWeights.set_size( 4, 1.0/24.0 );
        }
 
// ----------------------------------------------------------------------------
    } /* namespace integration */
} /* namespace belfem */
 
#endif //BELFEM_FN_INTPOINTS_GAUSS_TET4_HPP