I need to compare a compressed sensing algorithm with two different sensing matrices . Thus,I need to compute the mutual information between the original signal X and the compresssed signal y=Φx. I tried the following code

https://www.mathworks.com/matlabcentral/fileexchange/35625-information-theory-toolbox

But it works only when the two vectors are of the same size. Of Course,x and y are not with the same length. How can I compute the mutual information between them ?