Inherit from boost::matrix

Question

I would like to inherit from boost::matrix to enrich with some methods. I started with this :

#include <boost/numeric/ublas/matrix.hpp>

using namespace boost::numeric::ublas;

class MyMatrix : public matrix<double>
{
public:
    MyMatrix() : matrix<double>(0, 0) {}

    MyMatrix(int size1, int size2) : matrix<double>(size1, size2) {}

    MyMatrix(MyMatrix& mat) : matrix<double>(mat) {}

    MyMatrix(matrix<double>& mat) : matrix<double>(mat) {}

    MyMatrix& operator=(const MyMatrix& otherMatrix)
    {
        (*this) = otherMatrix;
        return *this;
    }
};

that allows me do to stuff like:

MyMatrix matA(3, 3);
MyMatrix matB(3, 3);
MyMatrix matC(matA);

but I may missed something because I am not able do to:

MyMatrix matD(matA * 2);
MyMatrix matE(matA + matB);

that causes:

error: conversion from 'boost::numeric::ublas::matrix_binary_traits<boost::numeric::ublas::matrix<double>, boost::numeric::ublas::matrix<double>, boost::numeric::ublas::scalar_plus<double, double> >::result_type {aka boost::numeric::ublas::matrix_binary<boost::numeric::ublas::matrix<double>, boost::numeric::ublas::matrix<double>, boost::numeric::ublas::scalar_plus<double, double> >}' to non-scalar type 'MyMatrix' requested

How can I use the methods from boost::matrix without redefining all of them inside MyMatrix ?

Did you verify that the class you want to inherit from has a virtual destructor? It's usually best to just write some free functions. — sweenish, Dec 08 '21 at 21:06
Does this answer your question? [Thou shalt not inherit from std::vector](https://stackoverflow.com/questions/4353203/thou-shalt-not-inherit-from-stdvector) — Karl Knechtel, Dec 08 '21 at 21:07
Not sure if it's getting the intended effect across, as the top and accepted answer says to just do it. I feel like that's horrible advice. — sweenish, Dec 08 '21 at 21:14
I don't now much about `boost::numeric::ublas`. Can you please tell us what you want to add to it? You don't need any of those functions to make the example code work. — Ted Lyngmo, Dec 08 '21 at 21:24
I would like to add some user defined methods to get (for example, but not only) minimum, maximum, mean, standard deviation of the values inside the matrix. — dagnic, Dec 08 '21 at 21:27

score 1 · Accepted Answer · answered Dec 08 '21 at 21:28

You don't need any of your additions to make this work:

MyMatrix matA(3, 3);
MyMatrix matB(3, 3);
MyMatrix matC(matA);

MyMatrix matD(matA * 2);
MyMatrix matE(matA + matB);

You only need to bring the boost::numeric::ublas::matrix<double> constructors and assignment operators into your derived class:

#include <boost/numeric/ublas/matrix.hpp>

class MyMatrix : public boost::numeric::ublas::matrix<double> {
public:
    using matrix<double>::matrix;    // use the constructors already defined
    using matrix<double>::operator=; // and the operator=s already defined

    // put your other additions here (except those you had in the question)
};

Demo

Inherit from boost::matrix

1 Answers1