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/*
* 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
*/
#ifndef __SIM_LINEAR_SOLVER_HH__
#define __SIM_LINEAR_SOLVER_HH__
#include <cassert>
#include <sstream>
#include <string>
#include <vector>
/**
* This class describes a linear equation with constant coefficients.
* The equation has a certain (variable) number of unkowns and it can hold
* N+1 coefficients.
*/
class LinearEquation {
public:
LinearEquation(unsigned unknowns) {
eq = std::vector <double> (unknowns + 1, 0);
}
// Add two equations
LinearEquation operator+ (const LinearEquation& rhs) {
assert(this->eq.size() == rhs.eq.size());
LinearEquation res(this->eq.size() - 1);
for (unsigned i = 0; i < res.eq.size(); i++)
res.eq[i] = this->eq[i] + rhs.eq[i];
return res;
}
// Multiply the equation by a constant
LinearEquation & operator*= (const double cnt) {
for (auto & c: eq)
c *= cnt;
return *this;
}
// Access a certain equation coefficient
double & operator[] (unsigned unkw) {
assert(unkw < eq.size());
return eq[unkw];
}
// Get a string representation
std::string toStr() const {
std::ostringstream oss;
for (unsigned i = 0; i < eq.size(); i++) {
if (i)
oss << " + ";
oss << eq[i];
if (i != eq.size() - 1)
oss << "*x" << i;
}
oss << " = 0";
return oss.str();
}
// Index for the constant term
unsigned cnt() const { return eq.size() - 1; }
private:
/** Coefficients */
std::vector <double> eq;
};
class LinearSystem {
public:
LinearSystem(unsigned unknowns) {
for (unsigned i = 0; i < unknowns; i++)
matrix.push_back(LinearEquation(unknowns));
}
LinearEquation & operator[] (unsigned eq) {
assert(eq < matrix.size());
return matrix[eq];
}
std::string toStr() const {
std::string r;
for (auto & eq: matrix)
r += eq.toStr() + "\n";
return r;
}
std::vector <double> solve() const;
private:
std::vector < LinearEquation > matrix;
};
#endif
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