problem with for and function inside other function

Question

camilo 2014-9-14

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/154820-problem-with-for-and-function-inside-other-function

回答： Mike Hosea 2014-9-26

采纳的回答： Mike Hosea

在 MATLAB Online 中打开

hello, i do not handle very much with matlab so i'm asking for help...

i have this for...

for i=1:n1

    t=0:0.001:Tp;
    p=@(t)((t<=1).*(0)+((t>1)&(t<=1.4)).*(100*sin(2*pi()*(t-1)/T))+(t>1.4).*(0));
    cos1=@(t)cos(2*pi()*i*(t)/Tp);
    sin1=@(t)sin(2*pi()*i*(t)/Tp);
    a0=(1/Tp)*quad(p,0,Tp);%constant
    pp1=@(t)a0;
    qa1=quad(p.*cos1,1,1.4);
    a1(i)=(2/Tp)*qa1;
    qb1=quad(p.*sin1,1,1.4);
    b1(i)=(2/Tp)*qb1;
    pp1=pp1+a1(i)*cos(2*pi()*i*t/Tp)+b1(i)*sin(2*pi()*i*t/Tp);

end

n1 and Tp are defined before the for. The error is with the qa1=quad(p.*cos1,1,1.4); i think i don't know how to multiply functions

also, i dont know if the last line "pp1=pp1+a1(i)*cos(2*pi()*i*t/Tp)+b1(i)*sin(2*pi()*i*t/Tp);" is corectly wrote

sorry for bad english, hope you can help me

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Answer 1

Mike Hosea 2014-9-26

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https://ww2.mathworks.cn/matlabcentral/answers/154820-problem-with-for-and-function-inside-other-function#answer_153004

在 MATLAB Online 中打开

Do not use QUAD. Use INTEGRAL. If you don't have INTEGRAL because your version of MATLAB is too old, use QUADGK.

Functions cannot be multiplied in MATLAB. To define a new function that is the product of the return values of two other functions, p and cos1, you should write

qa1 = integral(@(t)p(t).*cos1(t),1,1.4)

You can store that function in a variable if it seems clearer.

pc = @(t)p(t).*cos1(t);
qa1 = integral(pc,1,1.4);

.

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Answer 2

Youssef Khmou 2014-9-15

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/154820-problem-with-for-and-function-inside-other-function#answer_151695

From your description , the error occurs when you calculate the integral of pxcos1 from 1 to 1.4, that is the quad function, you have to mention what the error says, is times Matrix dimensions must agree? if it is the case then you need adjust the length of p or cos1.