variable size signal and upper bound

I want to generate scl codes of function that brought it bellow.but when i check subsystem compatibility i face with this error"Data 'S' is inferred as a variable size matrix, while its properties in the Model Explorer specify its size as inherited or fixed. Please check the 'Variable Size' check box and specify the upper bounds in the size field." what i should be do?

function S=fan(m,p,A,B,C) S=zeros(p,m); for i=1:p for j=1:i S(i,j)=C*A^(i-j)*B end end S=S(:,1:m);