I need help using embedded matlab functions for an iterative learning controller

I am working with a learning controller for a motor for a periodic signal. I want to store the followerror on each time sample during the first period, in a vector. Then I want to output these values the next period, and also rewrite them with the new followerror.

currently I am using:

function y = fcn(u,t)
%#codegen

d=round(t); 
z=zeros(1,99999); 
y=z(1,d+1);
z(1,d+1)=u;

t is a time counter that resets every period

but this doesn't seem to work, it keeps showing zero... Can anyone help me?

Answer 1

[Kaustubha Govind]

You are using the variable 'z' as a state, but note that the line:

   z=zeros(1,99999);

is executed at every time-step, so 'z' is reset to all zeros every time. You might want to define 'z' as a persistent variable instead:

function y = fcn(u,t)
%#codegen

persistent z;
d=round(t); 
if isempty(z)
  z=zeros(1,99999); 
end
y=z(1,d+1);
z(1,d+1)=u;

PS: You might also want to look into whether you are assigning 'z' correctly, you are using y=z(1,d+1), but z(1,d+1)=u; only on the next line. Did you mean to say y=z(1,d)?