how can I have a differentiate of length n in S-function Simulink

I am new to Simulink and I used an S-function in order to write my code. I need to numerically differntiate a vector of length n. The problem is that it diff return a vector of length n-1 and I get keep error of having an empty differentiate matrix. I do not know how to take of this in Simulink. Is there any function that returns differentiate with length n?

Answer 1

[Birdman]

You may try this:

https://www.mathworks.com/help/matlab/ref/gradient.html

[Mary]

Thank you, I have tried this but it returns a 2*1 matrix instead of 1*1.