How to define a matrix with each element a fixed size vector?

Hi, how could I define a boost::ublas::matrix with each element a fixed size vector?

I try to define it by

Code:

matrix< vector<double, 3> > double_matrix ;

but get the following error:

Code:

main.cpp:18: error: template argument 1 is invalid
main.cpp:18: error: template argument 3 is invalid
main.cpp:18: error: expected unqualified-id before ‘>’ token

Actually, the following code doesn't work too, getting the same error:

Code:

matrix< vector<double> > double_matrix ;

So, matrix doesn't support this type of declaration?

Thanks!

>> with each element a fixed size vector?
If it's fixed size why bother with a vector? Make a struct with three doubles, or a class and overload some operators if you want random access. eg:

Code:

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

struct my_doubles {
  double a, b, c;
};

int main() {
  boost::numeric::ublas::matrix<my_doubles> myd;

  return 0;
}