Put this line in your code:
inputMatrix = input('Input matrix in standard MATLAB format: ')
Hopefully your user knows that this means they should type something like
[1 2; 3 4]
in response to that. (If not, you need more explicit instructions as part of the input prompt.)
Then, you can use the variable inputMatrix in your code to calculate whatever you want and display it back:
outputMatrix = 2 * inputMatrix;
disp(outputMatrix)
