fn_ddpolyval.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_DDPOLYVAL_HPP
#define BELFEM_FN_DDPOLYVAL_HPP
 
#include "typedefs.hpp"
#include "cl_Vector.hpp"
 
namespace belfem
{
    template < typename T >
    T
    ddpolyval( const Vector< T > & aCoeffs, const T aX )
    {
        const index_t tN = aCoeffs.length() - 1;
        if ( tN < 2 )
        {
            return ( T ) 0;
        }
        T tPow = ( T ) tN;
        T aResult = tPow * ( tPow - ( T ) 1 ) * aCoeffs( 0 );
        for( index_t k=1; k < tN - 1; ++k )
        {
            aResult *= aX;
            tPow -= ( T ) 1;
            aResult += tPow * ( tPow - ( T ) 1 ) * aCoeffs( k );
        }
        return aResult;
    }
}
#endif //BELFEM_FN_DDPOLYVAL_HPP