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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