eb40af3bd4
Change-Id: I09a6117772c092157bf83701cf853145bb88ccf8 Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/25411 Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu> Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br> Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu> Tested-by: kokoro <noreply+kokoro@google.com>
86 lines
3.6 KiB
C++
86 lines
3.6 KiB
C++
/*
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* Copyright (c) 2015 ARM Limited
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* All rights reserved
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*
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* The license below extends only to copyright in the software and shall
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* not be construed as granting a license to any other intellectual
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* property including but not limited to intellectual property relating
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* to a hardware implementation of the functionality of the software
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* licensed hereunder. You may use the software subject to the license
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* terms below provided that you ensure that this notice is replicated
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* unmodified and in its entirety in all distributions of the software,
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* modified or unmodified, in source code or in binary form.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "sim/linear_solver.hh"
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std::vector <double>
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LinearSystem::solve() const
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{
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// Solve using gauss elimination, not ideal for big matrices
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std::vector < LinearEquation > smatrix = this->matrix;
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unsigned order = smatrix.size();
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for (unsigned row = 0; row < order - 1; row++) {
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// Look for a non-zero row, and swap
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for (unsigned i = row; i < order; i++) {
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if (smatrix[i][row] != 0.0f) {
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if (i != row) {
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LinearEquation tmp = smatrix[i];
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smatrix[i] = smatrix[row];
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smatrix[row] = tmp;
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}
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break;
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}
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}
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// Divide row by leading number to make it 1.0
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smatrix[row] *= (1.0f / smatrix[row][row]);
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// Add it (properly scaled) to the rows below
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for (unsigned i = row + 1; i < order; i++) {
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LinearEquation t = smatrix[row];
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t *= -1.0f * smatrix[i][row];
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smatrix[i] = smatrix[i] + t;
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}
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}
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// smatrix is now a triangular matrix with diagonal being 1
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// Just backproagate variable values from order-1 till 0
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std::vector <double> ret(order, 0.0f);
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for (int row = order - 1; row >= 0; row--) {
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// Unknown value
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ret[row] = -smatrix[row][smatrix[row].cnt()] / smatrix[row][row];
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// Propagate variable in the cnt term
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for (int i = row - 1; i >= 0; i--) {
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smatrix[i][smatrix[i].cnt()] += ret[row] * smatrix[i][row];
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smatrix[i][row] = 0.0f;
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}
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}
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return ret;
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}
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