Erro in using "from file" in simulink

Hi everyone, I'm new to simulink and matlab (so please answer me in detail) I'm loading a .mat file, send it to a matlab function (that send out the input) and I want to save it in another .mat file. But I don't know why input(99941*1) and output(99941*51) are different.(column in input repeated 51 times in output). Tnx