A numerical matrix is called 'diagonal' If all the elements outside of the top$-$left to bottom$-$right diagonal are equal to zero. For example:

Is a diagonal matrix, while.

Is not diagonal.

Given a square $2-$dimensional int array called matrix, where both row and column numbers are equal to the value stored in the int variable n$.$ Assign to the bool variable isDiagonal $($already declared but not initialized$)$ true if the matrix is diagonal, false otherwise.

Each elementis. Write a test program that prompts the user to enter two $3-$by$-3$ matrices and displays their addition.

Sample Run

Enter matrix$1$: $123456789$

Enter matrix$2$: $02314\mathrm{.}52\mathrm{.}21\mathrm{.}14\mathrm{.}35\mathrm{.}2$

The addition of the matrices is

$123024147$

$456+14\mathrm{.}52\mathrm{.}2=59\mathrm{.}58\mathrm{.}2$

$7891\mathrm{.}14\mathrm{.}35\mathrm{.}28\mathrm{.}112\mathrm{.}314\mathrm{.}2$