C++ casting static two-dimensional double array to double**

Question

I have such matrix in my program:

double m[3][4] = 
    {
        {2, 4, 5, 7},
        {4, 5, 1, 12},
        {9, 12, 13, -4}
    };

And I\'d

Answer 1

You can't just cast the array. You are going to have to create something like this:

double m[3][4] = 
    {
        {2, 4, 5, 7},
        {4, 5, 1, 12},
        {9, 12, 13, -4}
    };

double *marray[3] = {m[0],m[1],m[2]};
calculate(marray,3);

Or you can use a loop:

const size_t n = 3;
double *marray[n];
for (size_t i=0; i!=n; ++i) {
    marray[i] = m[i];
}
calculate(marray,n);

Answer 2

You can't.

The notation double** refers to an array of pointers. You don't have an array of pointers, you have an array of arrays of doubles.