MATLAB: How to call m-file in block simulink model??

pdes m-filesimulink

i have written the m-file to solve numerically a system of 4 partial differential equations which represent the infrared food dryer, and i have gotten result from that. the m-file that i wrote for this system has 4 function, one is for initial conditions of the equations, one is for the boundary conditions of the equations , one function is for main factors of the equations and last function gather all these functions and sole the equations. now , i want to connect a controller to this dryer in order to control the temperature of the emitter, so i need to put the m-file solution of the PDEs in the block simulink in order to connect with the controller block. i used s-function and matlab function to do that, but i got errors and i couldn't get result from that.

Best Answer

I think you are doing something wrong. I've been using m-files in Simulink to avoid the extra work of block-building what I have in a m-file, and some times it gets tricky, but if done with care, it should work. Since you do not give more info on how you are doing what you are doing, I can not help you out more. Check that your functions are in the proper directory and rightly linked.

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MATLAB: M-file function

Your function is calling itself without approaching any convergance or something that will allow it to end. Therefore it will run forever and eventually out of memory (hence the error). Try splitting it up into a script and a function as so:

Script:

 %creating window of plot from -5 to 50 using stepsize 0.25 for t x-axis
 %t should be on the x axis, v should be on the y axis
 k=0; 
for i= -5:.25:50
    k = k+1;
    t(k)=i;
    v(k)=vPieceWise(t(k));
end 
plot(t,v);
 
figure
plot(t,v);
hold on

Function:

%Part A: Mfile function to compute v as a function of t
function v = vPieceWise(t)
 if (t < 0)
        v = 0;
    elseif (0 <= t)&&(8<=16)
        v = -5*t+10*t.^2;
    elseif (8<=16)&&(t<=16)
        v = 624 - 3*t;
    elseif (t<=16)&&(t<=26)
        v = 12*(t-16).^2+36*t;
    elseif (26<t)
        v = 2136*exp(-0.1*(t-26));
 end

MATLAB: Pdepe: Spatial discretization has failed. Discretization supports only parabolic and elliptic equations, with flux term involving spatial derivative.

Your boundary conditions (BC) are specified incorrectly; a qr(i) value of zero and pr(i)=constant is not a valid BC.

Since you did not provide a mathematical description of your problem, it is impossible to say what the correct BC should be. Do you perhaps want pr(2)=ur(2)-1 and pr(3)=ur(3)-1?

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MATLAB: M-file function

MATLAB: Pdepe: Spatial discretization has failed. Discretization supports only parabolic and elliptic equations, with flux term involving spatial derivative.

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