add a function to a model

Hi, I develop a function in matlab code:

function u = f(y)
  if (u>0.8)
      y=1;
  elseif (u<0.8)
      y=-1;
  else
      y=0;

where u is a random signal generate with the random number block. How can i join these two blocks? (random number and a block which contain my function without errors). I try using level-2 matlab s-function but it make error. can i use another block in which i introduce my matlab function code?

Thanks in advance. Néstor

Answer 1

[Fangjun Jiang]

Use the "MATLAB Fcn" or "Fcn" block from library Simulink>User-Defined Functions.

Answer 2

[Daniel Baboiu]

If a function is coded as function u = f(y), then y is the argument and u is the return value. Your block of code does it the other way around.

[Néstor Monedero]

Sorry, the matlab function code is:

function y = fnc(u)

if(u<0.8)

y=-1;

elseif (u>0.8)

y=1;

else

y=0;

end

Answer 3

[Jon]

Have you tried using a 'MATLAB Function' block? Under 'User-Defined Functions'.

http://www.mathworks.com/help/toolbox/simulink/ug/f6-6010.html

u will be your input port and y will b your output port.

[Néstor Monedero]

Thanks, i use the matlab function block.