How to evaluate my integral
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I tried to evaluate this integral:
∫exp(7.313 x)/√(x^2+1.7439)dx on the interval 0 to 0.001.
Then I had this kind of error : Unexpected MATLAB expression. So how do I write and evaluate it?
Thank you.
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Accepted Answer
Star Strider
on 10 Apr 2014
I suggest:
f = @(x) exp(7.313.*x)./sqrt(x.^2+1.7439);
fi = integral(f, 0, 0.001)
produces:
fi =
760.0254e-006
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Star Strider
on 11 Apr 2014
Good catch!
Didn’t see that. I assumed ‘copy and paste’ meant everything.
More Answers (1)
Matt Tearle
on 10 Apr 2014
Hard to say what's causing the error without seeing the actual MATLAB code you used. But regardless, if you just want the numerical value, you can do that using integral (or similar functions):
f = @(x) exp(7.313*x)./sqrt(x.^2+1.7439);
integral(f,0,0.001)
The first line creates a function handle that defines the function of a single variable (x). Note the use of vector operations (such as ./) because integral will evaluate the integrand at a bunch of points simultaneously.
The second line uses integral to do the quadrature.
(You can also do symbolic integration with Symbolic Toolbox.)
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