Is this homework? Sounds like it. As you know, to do a matrix multiplication you need to have the number of columns of the first matrix equal the number of rows of the first matrix. You can use the size() function and an if statement to do this check. This is probably what your instructor meant. If you want to do an element by element multiplication you need to have both the number of rows match, and the number of columns match. But it's the same process - use size() and then test with "if". I'll leave the simple details up to you since I think it's your homework.
A way to do it that is probably not what your instructor is thinking of is to use try catch and let MATLAB automatically decide if they can be multiplied or not:
try
AB = A * B;
catch ME
errorMessage = sprintf('Matrices cannot multiply.\nError in function %s() at line %d.\n\nError Message:\n%s', ...
ME.stack(1).name, ME.stack(1).line, ME.message);
fprintf(1, '%s\n', errorMessage);
uiwait(warndlg((errorMessage));
end
Best Answer