Question

How can I define a array of boost matrices as a member variable?

None of the following worked.

boost::numeric::ublas::matrix<double> arrayM(1, 3)[arraySize];
boost::numeric::ublas::matrix<double>(1, 3) arrayM[arraySize];
boost::numeric::ublas::matrix<double> arrayM[arraySize](1, 3);

Thanks,
Ravi.

Answer 1

The size you initialize it with has nothing to do with the type. Therefore:

// this makes things easier!
typedef boost::numeric::ublas::matrix<double> matrix_type;

// this is the type (no initialization)
matrix_type arrayM[arraySize];

The problem comes with initializing the array. You can’t do this:

TheClass::TheClass() :
arrayM(1, 3) // nope
{}

Instead, you have to let them default-construct, then resize them all:

TheClass::TheClass()
{
    std::fill(arrayM, arrayM + arraySize, matrix_type(1, 3));
}

---

Since you’re using boost, consider using boost::array, since it gives a nicer syntax:

typedef boost::numeric::ublas::matrix<double> matrix_type;
typedef boost::array<matrix_type, arraySize> matrix_array;

matrix_array arrayM; // ah

TheClass::TheClass()
{
    arrayM.assign(matrix_type(1, 3));
}