make matrix equal comparable

Author: mgroncki

ql/math/matrix.hpp

@@ -60,6 +60,9 @@ namespace QuantLib {
 
         Matrix& operator=(const Matrix&);
         Matrix& operator=(Matrix&&) noexcept;
+
+        bool operator==(const Matrix&) const;
+        bool operator!=(const Matrix&) const;
         //@}
 
         //! \name Algebraic operators
@@ -255,6 +258,15 @@ namespace QuantLib {
         return *this;
     }
 
+    inline bool Matrix::operator==(const Matrix& to) const {
+        return rows_ == to.rows_ && columns_ == to.columns_ &&
+               std::equal(begin(), end(), to.begin());
+    }
+
+    inline bool Matrix::operator!=(const Matrix& to) const {
+        return !(this->operator==(to));
+    }
+
     inline void Matrix::swap(Matrix& from) {
         using std::swap;
         data_.swap(from.data_);