The assignment is to "... create a function that operates on two arguments, performing one of the operations 'plus', 'minus', 'times', 'power', 'ldivide' or 'rdivide' (specified as the 3rd argument), after it has matched the sizes of first two input arguments." So you have to make a functions that performs one of the basic math operations on two input arguments, and which operation it should be is determined by the 3rd input argument. You are lucky that nowadays Matlab itself tries to match the size of the input arguments of those operations. So if you add a scalar to a vector, the program is that smart that it uses the scalar term for all vector terms. And when the 1st argument is a column vector, it is used for all columns of matrix when the 2nd argument is a matrix that has an equal number of rows as the column has. When this 'problem' was created, Matlab did not do that by itself, and you had to take care of that yourself. So the problem is is even easier than you may think. See 'help ops' for basic math in Matlab.