/**++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 *
 *                                              PANIC
 *                              Portable Algorithms and Numerics In C++
 *
 *                       Scientific computing from scratch, with feeling.
 *
 * Copyright (c) 2026 Michelle Bausager
 *
 * This file is part of PANIC.
 *
 * PANIC is free software licensed under the GNU General Public License v3.0 or later.
 * You may redistribute and/or modify it under the terms of the GPL.
 *
 * PANIC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the LICENSE file for the full license text.
 *
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 *++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 *
 * Project Name:      PANIC
 * Module Name:       math
 * File Name:         matmul.hpp
 * Revision:          0.1.0
 * Date:              24-06-2026
 * Author:            Michelle Bausager
 *
 * Description:
 * Functions to print out tensors with std::cout << x std::endl;
 *
 *++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/
#pragma once
//---------------------------------------------------------------------------------------------------------------------------
// INCLUDE DESCRIPTION
//-----------------------------------------------------------------------------------------------------
#include <tensor/matrix.hpp> // for panic::real_matrix
//---------------------------------------------------------------------------------------------------------------------------
// DEFINE DESCRIPTION
//---------------------------------------------------------------------------------------------------------------------------

//---------------------------------------------------------------------------------------------------------------------------
// VARIABLE DESCRIPTION
//---------------------------------------------------------------------------------------------------------------------------

//---------------------------------------------------------------------------------------------------------------------------
// FUNCTION PROTOTYPE
//---------------------------------------------------------------------------------------------------------------------------
namespace panic{
namespace math{

/**
 * @brief Calculates matrix multiplication of two matrices.
 *
 * Computes:
 * @code
 * C(n, p) = A(n,m) + B(m,p)
 * @endcode
 *
 * @tparam T Numeric element type.
 * @param A First matrix.
 * @param B Second matrix. @ p B.rows needs to be the size of @p A.cols.
 * @param C Output matrix. Resized to C(A.rows, B.cols).
 *
 * @return true if @p C was resized and filled successfully.
 * @return false if resizing @p C failed or A==B.
 *
 * @note This overload writes the result into an existing matrix to avoid
 *       unnecessary temporary allocations.
 */
template <typename T>
bool matmul(const panic::tensor::matrix<T>& A, const panic::tensor::matrix<T>& B, panic::tensor::matrix<T>& C);

/**
 * @brief Returns a new matrix of multiplication of two matrices.
 *
 * Computes:
 * @code
 * result(n, p) = A(n,m) + B(m,p)
 * @endcode
 *
 * @tparam T Numeric element type.
 * @param A First matrix.
 * @param B Second matrix. @ p B.rows needs to be the size of @p A.cols.
 *
 * @return A new matrix containing the result.
 * @return An empty vector if the operation fails.
 *
 * @note This overload is convenient, but may allocate a new matrix.
 */
template <typename T>
panic::tensor::matrix<T> matmul(const panic::tensor::matrix<T>& A, const panic::tensor::matrix<T>& B);


} // namespace math
} // namespace panic