Write a function m-file that takes as input a matrix a and a vector x, and as output gives the product y = ax by row, as defined above (hint: use a for loop to define each entry of the vector y.) your m-file should perform a check on the dimensions of the input variables a and x and return a message if the dimensions do not match. call the file myrowproduct. m. note that this file will not be the same as the myproduct. m example. test your function on a random 4 × 4 matrix a and a random 4 × 1 vector x. compare the output with a*x.