Dynamically Allocated mpfr_t matrix with std::vector

Question

I want to have a class that works as a matrix of mpfr_t elements. I thought STL Vectors would be a great idea for dynamically allocating as many of these as I want, but I get some errors here.

#ifndef GMPMATRIX_H
#define GMPMATRIX_H

#include <vector>
#include <mpfr.h>

typedef std::vector<mpfr_t> mpVector;
typedef std::vector<mpVector> mpMatrix;

class GmpMatrix
{
    private:
        int n;
        int m;
        mpMatrix elements;

    public:
        GmpMatrix() {}
        GmpMatrix(int n, int m)
        {
            this->n = n;
            this->m = m;

            for (int i = 0; i < n; ++i)
            {
                mpVector e_push(m);
                for (int j = 0; j < m; ++j)
                {
                    mpfr_t e;
                    mpfr_init(e);
                    e_push.push_back(e);
                }
            }
        }


        ~GmpMatrix() {}
};

#endif // GMPMATRIX_H

The errors are:

   /usr/include/c++/5/ext/new_allocator.h:120:4: error: parenthesized initializer in array new [-fpermissive]
      { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
        ^
    /usr/include/c++/5/ext/new_allocator.h:120:4: error: no matching function for call to ‘__mpfr_struct::__mpfr_struct(const __mpfr_struct [1])’

I've really looked into this and I can't figure it out. Is there a way to make a vector< vector<mpfr_t> > work? Does anyone know what is happening?

Answer 1

mpfr_t is a C-style array type. You cannot store those in std::vector.

You can wrap mpfr_t in a simple struct and store those.