Set initial value in Matlab Function block

How can I set the initial value for UP? UPI is my initial value input to the block. How can I make sure UP will accepts thhs value only once (start of the simulation)? Thanks

funciton UP=[UPI]
*UP=UPI;
%#close safety_relieve_valve
  SRV=0;
  if (UP>UL) 
      Val=0;
      UP=RD;
  else
      Val=1;
      UP=RU;
  end
  if (UP<LL) & (Val==0)
      UP=RD+0.1;
      disp(UP);
      Val=1;
  elseif (UP>=LL) & (Val==1)
      UP=UP+0.1;
  end*

[William]

The issue of the if statement is resolved. Is there any block to extract a single element from the vector (entered from "From Workspace" block) to set as the input to the ML Fctn block?

[Azzi Abdelmalek]

What do you mean? the same single element each iteration, or the first, then the second, and so on ?

[William]

I am required to enter input interactively so I used the "From Workspace" block. This block can only input with vector instead of scalar value. I would like to extract a single element from this vector then.

[Azzi Abdelmalek]

have you tried Ports and Data Manager?

[William]

The input is set as Inherit: same as Simulink. I kept getting error "Expecting scalr...." I changed the type to "double" but no avail.

Answer 1

[Azzi Abdelmalek]

You can use persistent declaration

function UP=fcn(UPI)
persistent UPI1
if isempty(UPI1)
 UP=UPI
else
 UP=UPI1
end
%your code
UPI1=UP;

[William]

What is UP1 & UPI1?

Thanks.

[Azzi Abdelmalek]

UP1 does not exist (The answer was edited) UPI1 is an intermediate variable

[William]

Referring to my code above, my if (UP>UL) is not executed. I checked the value of UP & it is greater than UL during the simulation. Any suggestion?

Thanks.

[Azzi Abdelmalek]

What UL and other variables represent? If they are constants from workspace, use Ports and Data Manager

[William]

UL, LL & UPI are all constants. I tried different opitons with Port and Data manager but the "if (UP>UL) is still not executed. BTW, does size matter (it is currently set at -1)? Thanks.

[Azzi Abdelmalek]

What is the size of UL?

[William]

UL equals to 18 & its sapling size is inf.

[Azzi Abdelmalek]

its sapling size is inf ? what is that ?

[William]

I meant sampling time in the property box of constant block.

[William]

Instead of using the 'elseif' statement, I created another 'if' statement & it worked. But there are some other issues I would like to resolve. I will post it later. Thanks again.

[William]

function UP = UPC(t,LL,u1,u2,u3,u4,u5,u6,u7,u8)
%#codegen
persistent LLI
if isempty(LLI)
  UP=LL;
else
  UP=LLI;
end
My code
LLI=UP;

Azzi, I kept getting the error message "LLI is not defined..." when I attempted to run the simulation. "LL" is my IC for UP. Any idea? Thanks.

Answer 2

[Danilo Teran]

Hi

I have a similar problem, could you find a real solution.

Best regards?