I have a problem with integration "Error using / Matrix dimensions must agree"

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Filious
Filious 2019-11-6
评论： Filious 2019-11-7
syntax is here:
clc;clear all;close all;
m=input('input a value');
x=linspace(1,2,m);
%function
f=(x+(1/x)).^2;
%real value of integral
ff=@(x)(x+(1/x)).^2;
RV=integral(ff,1,2);
%Solution with numerical method (Trap method)
IT=Trap(x,f,m)
ybh=100*(abs(RV-IT)/RV
function IT=Trap(x,f,m)
IT=(x(m)-x(1))*(f(1)+f(m))/2
return
end
Why this isnt working?
ERROR:
input a value2
Error using /
Matrix dimensions must agree.
Error in odev (line 5)
f=(x+(1/x)).^2;
Thank you.

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采纳的回答

Fabio Freschi
Fabio Freschi 2019-11-6
When you define your functions use ./ instead of /
%function
f=(x+(1./x)).^2;
%real value of integral
ff=@(x)(x+(1./x)).^2;
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Fabio Freschi
Fabio Freschi 2019-11-7
Maybe I got the point: your code does not exit with an error, but it produces the wrong result!
Your implementation of the trapezoidal rule is not correct. You are not using all your samples but only the first and last points. If you really don't want to use the built-in trapz, you can implement yourself as
Itrap = sum((f(2:end)+f(1:end-1)).*(x(2:end)-x(1:end-1))/2)

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