This operation can only be performed on an array

You can't use range variables i, j inside a program.
In a program you would have to use for-loops instead.

See if the calculation I appended at the end does what you intended.

I attached a version how I would do it and another one following the way you had chosen.
I also streamlined your row sum function as it was a bit unclear because of the double usage of the variable "j" and the inefficient and unnecessary inner loop. This function also does not require vectorization.

Prime 9 file attached