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Diffstat (limited to 'src/sim/linear_solver.cc')
| -rw-r--r-- | src/sim/linear_solver.cc | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/src/sim/linear_solver.cc b/src/sim/linear_solver.cc new file mode 100644 index 000000000..644490fb9 --- /dev/null +++ b/src/sim/linear_solver.cc @@ -0,0 +1,87 @@ +/* + * Copyright (c) 2015 ARM Limited + * All rights reserved + * + * The license below extends only to copyright in the software and shall + * not be construed as granting a license to any other intellectual + * property including but not limited to intellectual property relating + * to a hardware implementation of the functionality of the software + * licensed hereunder. You may use the software subject to the license + * terms below provided that you ensure that this notice is replicated + * unmodified and in its entirety in all distributions of the software, + * modified or unmodified, in source code or in binary form. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer; + * redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution; + * neither the name of the copyright holders nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * Authors: David Guillen Fandos + */ + +#include "sim/linear_solver.hh" + +std::vector <double> +LinearSystem::solve() const +{ + // Solve using gauss elimination, not ideal for big matrices + std::vector < LinearEquation > smatrix = this->matrix; + + unsigned order = smatrix.size(); + for (unsigned row = 0; row < order - 1; row++) { + // Look for a non-zero row, and swap + for (unsigned i = row; i < order; i++) { + if (smatrix[i][row] != 0.0f) { + if (i != row) { + LinearEquation tmp = smatrix[i]; + smatrix[i] = smatrix[row]; + smatrix[row] = tmp; + } + break; + } + } + + // Divide row by leading number to make it 1.0 + smatrix[row] *= (1.0f / smatrix[row][row]); + + // Add it (properly scaled) to the rows below + for (unsigned i = row + 1; i < order; i++) { + LinearEquation t = smatrix[row]; + t *= -1.0f * smatrix[i][row]; + smatrix[i] = smatrix[i] + t; + } + } + + // smatrix is now a triangular matrix with diagonal being 1 + // Just backproagate variable values from order-1 till 0 + std::vector <double> ret(order, 0.0f); + for (int row = order - 1; row >= 0; row--) { + // Unknown value + ret[row] = -smatrix[row][smatrix[row].cnt()] / smatrix[row][row]; + // Propagate variable in the cnt term + for (int i = row - 1; i >= 0; i--) { + smatrix[i][smatrix[i].cnt()] += ret[row] * smatrix[i][row]; + smatrix[i][row] = 0.0f; + } + } + + return ret; +} |