Differentiation of a data inside a Cell array

I have cell array called "s". Inside it there is only one data matrix. I need to do differentiation ( derivative) of that data ( which was inside the cell array s) with respect to the length of thr p matrix. To do the differentiation I used the following process. Is my approach correct ?

Thanks in ADVANCE !!

s = {rand(15,5)};
t = cell2mat(s);
a = diff(t);
p = [1 2 3];
q = a/length(p); % dx/dy form 

[Walter Roberson]

How does changes in the length of p cause t to behave differently? I would understand if p was the same length as the rows or columns, but it is not.

Answer 1

[Walter Roberson]

I suspect that what you want is

q = gradient(p, s{1})