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

matlab function blocksimulinkxsteam

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.

Best Answer

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.
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