I want to add together the cross-diagonal elements in a matrix. For example, I have a 3\*3 Matrix which is two dimensional, I want to convert it to one dimensional:

```
      -------------------
      |  1  |  2  |  3  |
      -------------------
 A=   |  4  |  5  |  6  |
      -------------------
      |  7  |  8  |  9  |
      -------------------

```

final output will be,

```
     ____ ____ ____ ____ ____
 B= |1   | 6  | 15 | 14 |  9 |
    |____|____|____|____|____|

```

First cross-diagonal `A[0][0]` will be copied to `B[0]`.

Then the next cross-diagonal elements `A[1][0]` and `A[0][1]` will be added and copied to `B[1]`, *i.e.* 4 and 2 will be added.

Then the next cross-diagonal elements `A[2][0]` and `A[1][1]` and `A[0][2]` will be added and copied to `B[2]`, *i.e.* 7, 5 and 3 will be added.

And so on...