Good day guys. How do I write a Matlab program that will integrate a nonlinear system over one sample period?

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ojonugwa adukwu 2019-3-29

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评论： ojonugwa adukwu 2019-3-29

I am trying to write a function that integrates a nonlinear model over one sample period. My outputs are next states (x1k1, x2k1). My inputs contain among others current states (x1k, x2k). I want to use the "int" command in matlab but, I am not getting it right. Below is my code.

function [x1k1,x2k1]=integr_S(x1k,x2k,uk,V,k1p,k2p,ca0,cb0,T)
% Calculates the next-state concentrations of the reactor given the
% input
syms ca0 x1k x2k k1p k2p cb0 uk V
fint1=(((ca0-x1k)*uk/V)-k1p*x1k);
fint2=(((cb0-x2k)*uk/V)-k2p*x2k);
x1k1=x1k+integral(fint1,t, 0, 1);
x2k1=x1k+integral(fint2,t 0, 1);

Please help.

Thanks

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Star Strider 2019-3-29

在 MATLAB Online 中打开

Try this:

syms ca0 x1k x2k k1p k2p cb0 uk V t x1k(t) x2k(t) 
fint1(t)=(((ca0-x1k(t))*uk/V)-k1p*x1k(t));
fint2(t)=(((cb0-x2k)*uk/V)-k2p*x2k(t)+k1p*x1k(t));
x1k1=x1k+int(fint1,t,0,1);
x2k1=x1k+int(fint2,t,0,1);

You need to define all the variables numerically to get a numeric result. Your numeric variables must either be defined after the syms call, or be omitted from the syms call.

For an extended discussion of symbolic variables, see: Symbolic Computations in MATLAB (link).

ojonugwa adukwu 2019-3-29