How to define persistent matrix variable inside the Scilab function?

Question

I have been developing a Scilab function where I need to have persistent variable of the matrix type. Based on my similar question I have chosen the same approach. Below is the code I have used for test of this approach.

function [u] = FuncXYZ(x)

global A;
global init;

if init == 0 then
   init = 1;
   A = eye(4, 4);
endif

u = A(1, 1);

endfunction

As soon as I have integrated the function inside my Xcos simulation I have been surprised that I see "0" at the output of the scifunc_block_m.

Nevertheless I have found that in case I use below given command for "return" from the function

u = A(3, 3);

the function returns really the expected "1". Additionaly if I take a look at the Variable Browser on the top right corner of the Scilab window I can't se the expected A 4x4 item. It seems that I am doing something wrong.

Can anybody give me an advice how to define a persistent variable of the matrix type inside the Scilab function? Thanks in advance for any ideas.

Please do not spam irrelevant tags. This doesn't have to do with neither MATLAB nor SimuLink. — Adriaan, Dec 12 '22 at 14:23
I don’t know scilab, in MATLAB you’d use `persistent`: https://www.mathworks.com/help/matlab/ref/persistent.html — Cris Luengo, Dec 12 '22 at 14:29

score 2 · Accepted Answer · answered Dec 13 '22 at 08:37

Global variables are by default initialized with an empty matrix. Hence, you should detect first call with isempty()

function [u] = FuncXYZ(x)
  global A;
  global init;
  if isempty(init)
    init = 1;
    A = eye(4, 4);
  end
  u = A(1, 1);
endfunction

BTW, your code is incorrect, there is no endif in Scilab.

How to define persistent matrix variable inside the Scilab function?

1 Answers1