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2013-04-07T21:32:26.060
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2017-05-23T11:56:00.120
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I don't really know why you wish to add up matrices of different dimensions, but in order to do it, you must turn the method into a method template on the dimension of the matrix argument: <pre><code>#include <type_traits> template <int Roz2> Matrix& operator+(Matrix<T,Roz2> b) { // check matrix argument size compatibility std::static_assert(Roz2 >= Roz, "incompatible matrices for operator+()"); Matrix<T,Roz> tmp; for(int i=0;i<Roz;++i) for(int j=0;j<Roz;++j) tmp.tab[i][j]=this->tab[i][j]+b.tab[i][j]; } </code></pre> Since <code>Matrix<T,0></code> is a specialization to handle dynamic dimension, you must specialize the operator for it: <pre><code>// in the generic template Matrix& operator+(Matrix<T,0> b) { assert (b.z < Roz, "incompatible dynamic matrix for operator+"); Matrix<T,0> tmp(b.Roz);; for(int i=0;i<Roz;++i) for(int j=0;j<Roz;++j) tmp.tab[i][j]=this->tab[i][j]+b.tab[i][j]; } </code></pre> and in <code>Matrix<T,0></code>: <pre><code>template <int Roz> Matrix& operator+(Matrix<T,Roz> b) { assert(Roz >= z,"...."); Matrix<T,0> tmp(b.z); for(int i=0;i<z;++i) for(int j=0;j<z;++j) tmp.tab[i][j]=this->tab[i][j]+b.tab[i][j]; } </code></pre> In the above solution, however, the operator is not commutative. In order to make it so, we need to do some change: <pre><code> // define a min operator as constexpr in case the existing one is not template<typename T> constexpr T const& rmin(T const& a, T const& b) { return a > b ? b : a; } // generic operator template <int Roz2> Matrix<T,rmin(Roz,Roz2)>& operator+(Matrix<T,Roz2> b) { constexpr int R = min(Roz,Roz2); Matrix<T,R> tmp; for(int i=0;i<R;;++i) for(int j=0;j<R;++j) tmp.tab[i][j]=this->tab[i][j]+b.tab[i][j]; } // specialized operator on Roz=0 argument Matrix<T,0>& operator+(Matrix<T,0> b) { const int r = min(z,b.z); Matrix<T,0> tmp(r); for(int i=0;i<r;;++i) for(int j=0;j<r;++j) tmp.tab[i][j]=this->tab[i][j]+b.tab[i][j]; } // specialized operator in Roz=0 template Matrix& operator+(Matrix<T,Roz> b) { return b + *this; } </code></pre> You will have to duplicate the code for <code>const &</code> parameters taking operators (or perhaps simply get rid of the non const parameter versions which don't seem very useful in that context). Note the use of a <a href="http://en.cppreference.com/w/cpp/language/static_assert" rel="nofollow noreferrer">static assert</a> to limit the use of the operator with matrices of equal or larger dimension (this is a C++11 feature) in the non commutative version of the operators. See <a href="https://stackoverflow.com/questions/5605142/stdmax-and-stdmin-not-constexpr">this question</a> on the topic of <code>min</code> not being a <code>constexpr</code> function template for further details.
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