Variable 'ep3' is undefined on some execution paths.

Hello dears,

I'm using the block named Embedded MATLAB (that link the simulink to matlab) and when I try to run the code above, return the message errors: "Variable 'ep3' is undefined on some execution paths", "Variable 'edotp3' is undefined on some execution paths". However, I define these parameters in the embedded matlab function. In below code I identified the line of error.

function y_3 = fcn3_2star_Edit_01(ys1,ys2)

de3=ys1
e3=ys2
  
 x0nb_up=-0.9;    x0z_up=-0.1;  x0pb_up=0.9;        
 x0nb=-1;         x0z=0;        x0pb=1;        
 x0nb_bot=-1.1;   x0z_bot=0.1;  x0pb_bot=1.1;       
  
%% x0z1=0; x0p=1; x0n=-1;
 
%%%% Mu&SigmaForMF %%%%
muP=1; muZ=0; muN=-1; sigma=0.0598957;            

                                                                    
 if e3<=x0pb && e3>0
   ep3=1*max(0,exp(-(e3-x0pb)^2/0.16))
 else
    if e3 <=0
       ep3=0;
    else  
        if e3 >x0pb
           ep3=1*max(0,1)
        end 
    end
end
 %%%%%  
                                                            
  if e3<=x0z && e3>x0nb
    ez3=1*max(0,exp(-(e3-x0z)^2/0.16));
else
    if e3>=x0z && e3<x0pb
        ez3=1*max(0,exp(-(e3-x0z)^2/0.16));
    else
        if e3<=x0nb
            ez3=0 ;
        else
            if e3>=x0pb
                ez3=0;
            end
        end
    end
 end 
%%%%% 
if e3<x0nb                            
   en3=1*max(0,1);
else
    if e3>=x0nb && e3<0
       en3=1*max(0,exp(-(e3-x0nb)^2/0.16));
    else
        if e3>=0
           en3=0;
        end
    end
end 
%%%%%%%%%%%%%%%%%%%%
if de3<=x0p && de3>0
    edotp3=1*max(0,exp(-(de3-x0p)^2/0.16));
else
    if de3 <=0
        edotp3=0;
    else
        if de3>x0p
           edotp3=1*max(0,1);
        end
    end  
end
%%%%%
if de3<=x0z && de3>x0nb
   edotz3=1*max(0,exp(-(de3-x0z)^2/0.16));
else
    if de3>=x0z && de3<x0pb
        edotz3=1*max(0,exp(-(de3-x0z)^2/0.16));
    else
        if de3<=x0nb
            edotz3=0 ;
        else
            if de3>=x0pb
                edotz3=0;
            end
        end
    end
end
%%%%%
if de3<x0n
    edotn3=1*max(0,1);
else
    if de3>=x0n && de3<0
       edotn3=1*max(0,exp(-(de3-x0n)^2/0.16));
    else
        if de3>=0
            edotn3=0;
        end
    end
end 
%%%%%%%%%%%%%%
if 0< ep3 && ep3 <1                 %%% The ERROR is in this line
   p_ep3=(1/((2*sqrt(2*pi))*ep3*sigma))*sqrt(-0.16/(log(ep3)))*(exp(-(sqrt(-0.16*log(ep3))+e3-muP)^2/(2*sigma^2))+exp(-(-sqrt(-0.16*log(ep3))+e3-muP)^2/(2*sigma^2)));
   PP_ep3=1-((erf((sqrt(-0.08*log(ep3))+(muP/(2^0.5))-(e3/(2^0.5)))/sigma)+erf((sqrt(2)*sqrt(-0.08*log(ep3))-muP+e3)/(sqrt(2)*sigma)))/(sqrt(2)))
   else
    p_ep3=0;
    PP_ep3 =0;
end
%%%%%%%%%%%%%%
if 0< edotp3 && edotp3 <1           %%% The ERROR is in this line
    p_edotp3=(1/((2*sqrt(2*pi))*edotp3*sigma))*sqrt(-0.16/(log(edotp3)))*(exp(-(sqrt(-0.16*log(edotp3))+de3-muP)^2/(2*sigma^2))+exp(-(-sqrt(-0.16*log(edotp3))+de3-muP)^2/(2*sigma^2)));
    PP_edotp3=1-((erf((sqrt(-0.08*log(edotp3))+(muP/(2^0.5))-(de3/(2^0.5)))/sigma)+erf((sqrt(2)*sqrt(-0.08*log(edotp3))-muP+de3)/(sqrt(2)*sigma)))/(sqrt(2)))
   
else
    p_edotp3=0;
    PP_edotp3=0;
end
%%%%%%

........ the code is continuded
    

My code is too longe, so I only put the beginig of it up to where there is problem.

Answer 1

[Jan]

The message "undefined on some execution paths" means, that there is a possible combination of IF-branches, in which the variable is not defined anywhere. The solution is to create a default value before the IF branchs. This oul simplify your code massively in addition.

Replace:

 if e3<=x0pb && e3>0
   ep3=1*max(0,exp(-(e3-x0pb)^2/0.16))
 else
    if e3 <=0
       ep3=0;
    else  
        if e3 >x0pb
           ep3=1*max(0,1)
        end 
    end
 end

by

ep3 = 0;
if e3 <= x0pb && e3 > 0
   ep3 = 1 * max(0, exp(-(e3 - x0pb)^2 / 0.16));  % "1*" ?!?
elseif e3 > x0pb
   ep3 = 1;   % "1*max(0,1)" ?!?
end

The other parts can be simplified also in an equivalent way. E.g.:

if de3<=x0z && de3>x0nb
   edotz3=1*max(0,exp(-(de3-x0z)^2/0.16));
else
    if de3>=x0z && de3<x0pb
        edotz3=1*max(0,exp(-(de3-x0z)^2/0.16));
    else
        if de3<=x0nb
            edotz3=0 ;
        else
            if de3>=x0pb
                edotz3=0;
            end
        end
    end
end

can be simpified to:

edotz3 = 0;
if (de3 <= x0z && de3 > x0nb) || ...
    de3 >= x0z && de3 < x0pb)
   edotz3 = exp(-(de3 - x0z)^2 / 0.16);
end

Note: max(0, exp(x)) is the same as exp(x), because the result is >= 0 in every case.

[azadeh jalali]

Thank you very much.