Euler's Method check

Question

Thierry Kayiranga 2013-6-3

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https://ww2.mathworks.cn/matlabcentral/answers/77841-euler-s-method-check

Hello, I am trying to model a first order ODE using Euler's Method. I have shown the Euler's step in the code below and I wanted somebody to double-check it and see if it is written correctly. All the R,C,L, Ron values are given. Thankx for the help

 h = 0.0001;                         % Adjustable time-step
 t = 0:h:0.002;
    for i = 1:length(t)-1 
        switch (switch_state)
            case 1
               k11 = x2(i)*1/L - x1(i)*1/(R*C);
               k12 = x2(i)*-Ron/L - x1(i)*1/L + Vi*1/L;
            otherwise
               k11 = x2(i)*1/L - x1(i)*1/(R*C);
               k12 = x2(i)*-Ron/L - x1(i)*1/L;
        end
        x1(i+1) = x1(i) + h*k11;
        x2(i+1) = x2(i) + h*k12;  
    end
 plot(t,x1)
 plot(t,x2)

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Answer 1

Iain 2013-6-3

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https://ww2.mathworks.cn/matlabcentral/answers/77841-euler-s-method-check#answer_87545

You've implemented euler's method correctly. Whether or not you have calculated k11 and k12 correctly, and chosen sensible values for h, and LCR is another question.

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Iain 2013-6-5

编辑：Iain 2013-6-5

They're not the same equations.

Remember, matrix multiplication is Row times column

But, yes, the euler implementation is correct providing that k1 is the differential of x.

Thierry Kayiranga 2013-6-6

Right. Row times column. Correct me if I'm wrong. So basically, the loop would take each row of A and multiply it by the corresponding column of x and add it B*Vi. And k1 would be [k11 k12]' from the earlier code. right?

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