c_affine_matrix_function.cpp

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/*
 *  SPDX-FileCopyrightText: Copyright 2021, Siavash Ameli <sameli@berkeley.edu>
 *  SPDX-License-Identifier: BSD-3-Clause
 *  SPDX-FileType: SOURCE
 *
 *  This program is free software: you can redistribute it and/or modify it
 *  under the terms of the license found in the LICENSE.txt file in the root
 *  directory of this source tree.
 */
 
 
// =======
// Headers
// =======
 
#include "./c_affine_matrix_function.h"
#include <cassert>  // assert
#include "../_c_basic_algebra/c_vector_operations.h"  // cVectorOperations
 
 
// ===========
// constructor
// ===========
 
 
template <typename DataType>
cAffineMatrixFunction<DataType>::cAffineMatrixFunction(
        const LongIndexType num_rows_,
        const LongIndexType num_columns_):
 
    // Base class constructor
    cLinearOperator<DataType>(num_rows_, num_columns_),
 
    B_is_identity(false)
{
    // This class has one parameter that is t in A+tB
    this->num_parameters = 1;
}
 
 
// ==========
// destructor
// ==========
 
 
template <typename DataType>
cAffineMatrixFunction<DataType>::~cAffineMatrixFunction()
{
}
 
 
// ==============
// get eigenvalue
// ==============
 
 
template <typename DataType>
DataType cAffineMatrixFunction<DataType>::get_eigenvalue(
        const DataType* known_parameters,
        const DataType known_eigenvalue,
        const DataType* inquiry_parameters) const
{
    assert((this->eigenvalue_relation_known == 1) && \
            "An eigenvalue relation is not known. This function should be "
            "called only when the matrix B is a scalar multiple of the "
            "identity matrix");
 
    // Shift the eigenvalue by the parameter
    DataType inquiry_eigenvalue = \
        known_eigenvalue - known_parameters[0] + inquiry_parameters[0];
 
    return inquiry_eigenvalue;
}
 
 
// =================
// add scaled vector
// =================
 
 
template <typename DataType>
void cAffineMatrixFunction<DataType>::_add_scaled_vector(
        const DataType* input_vector,
        const LongIndexType vector_size,
        const DataType scale,
        DataType* output_vector) const
{
    // Subtracting two vectors with minus scale sign, which is adding.
    cVectorOperations<DataType>::subtract_scaled_vector(
            input_vector, vector_size, -scale, output_vector);
}
 
 
// ===============================
// Explicit template instantiation
// ===============================
 
template class cAffineMatrixFunction<float>;
template class cAffineMatrixFunction<double>;
template class cAffineMatrixFunction<long double>;