I am trying to integrate the XSteam mfile in my simulink model through a MATLAB function block, only this error occurs: Variable 'hs' is undefined on some execution paths.

This is what my own function file looks like:

function h = fcn(t,p)
%#codegen
h=XSteam('h_pt',p,t);

And this is de part where the error is referring to in the XSteam mfile:

function h4L_p = h4L_p(p)
if (p > 0.000611657 & p < 22.06395)==1
    Ts = T4_p(p);
    if p < 16.529 
        h4L_p = h1_pT(p, Ts);
    else
        %Iterate to find the the backward solution of p3sat_h
        Low_Bound = 1670.858218;
        High_Bound = 2087.23500164864;
        ps=-1000;
        while abs(p - ps) > 0.00001
            hs = (Low_Bound + High_Bound) / 2;
            ps = p3sat_h(hs);
            if ps > p 
                High_Bound = hs;
            else
                Low_Bound = hs;
            end
        end
        h4L_p = hs;     ERROR OCCURS ON THIS LINE(line 2480 in XSteam)   

if true
  % code
end
    end
else
    h4L_p = -99999;
end

    if true
      % code
    end

The complete XSteam mfile can be found at:

http://www.mathworks.com/matlabcentral/fileexchange/9817-x-steam-thermodynamic-properties-of-water-and-steam

I already tried to place "persistent hs;" after function, but that didn't solve the problem.

[saladin ghanem]

Hi, I've found this code below and it worked for me.

function h10 = fcn(Pb)
%#codegen
coder.extrinsic('XSteam');
h10 = coder.nullcopy(zeros(size(Pb)));
h10=XSteam('hL_P',Pb);

You can change hL_P and play with you code. I hope you can make use of it.

[Anwer Hamed]

Thank you very much saladin you script solved my problem

Answer 1

[Vidhya Dharshini]

hi, when you are using a matlab function block always ensure that each output has its own execution path. for example cosider the following code

if(i>0)
y=10
else if(i<0)
y=5
end
when you run this inside a matlab function block you will get the error because what if the value i is a NaN. so always try to end your if statements with a simple else statement.This will solve your problem.

[Arnoud]

Thanks, I defined hs on places where it was not defined and now it works fine. thank you!

Answer 2

[Tarek Sobh]

Hello Arnoud, I'm basically trying to do the same thing, however, I'm getting the same errors that you used to get. Can you please elaborate on how you were able to solve the problem? Did you edit the XSteam.m file? Thanks.

[Juan Miguel Serrano Rodríguez]

Hi Tarek, probably you don't need this anymore but hopefully it might help someone else or yourself. What I did was check where the error was ocurring and found there is a while statement in which the hs is defined but it was being used outside of this while so if the condition of the loop was not met then h4V_p would equal to a variable which does not exist.

function h4V_p = h4V_p(p)
if (p > 0.000611657 & p < 22.06395)==1
    Ts = T4_p(p);
    if p < 16.529 
        h4V_p = h2_pT(p, Ts);
    else
        %Iterate to find the the backward solution of p3sat_h
        Low_Bound = 2087.23500164864;
        High_Bound = 2563.592004+5;
        ps=-1000;
        % hs not defined before while !! So add this line:
        hs = (Low_Bound + High_Bound) / 2;
        while abs(p - ps) > 0.000001
            hs = (Low_Bound + High_Bound) / 2;
            ps = p3sat_h(hs);
            if ps < p 
                High_Bound = hs;
            else
                Low_Bound = hs;
            end
        end
        % so it may not exist when used here
        h4V_p = hs;
    end
else
    h4V_p = -99999;
end

Answer 3

[saladin ghanem]

Hi, I've found this code below and it worked for me.

function h10 = fcn(Pb)
%#codegen
coder.extrinsic('XSteam');
h10 = coder.nullcopy(zeros(size(Pb)));
h10=XSteam('hL_P',Pb);

You can change hL_P and play with you code. I hope you can make use of it.