How to get rid of "exponential integral function, Ei(x)" in symbolic math integrartion?!

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Antonio 2015-12-16

评论： Walter Roberson 2015-12-16

Hi,

I'm trying to calculate the integral of the following f(x) in MATLAB:

f(x) = -m/(x*e^mx)

When I write something like this:

syms x m e
int(-m/(x*(e^(m*x))), x)

I get my answwer as a function of exponential integral function, which is ans = m*Ei(1, m*x*log(e))

How can I get rid of Ei(x) and find an exact solution to my problem?

Thanks

Antonio 2015-12-16

Thanks Torsten ...

Walter Roberson 2015-12-16

You probably want

int(-m/(x*(exp(m*x))), x)

You will still get Ei but you will get a simpler solution that does not depend upon the undefined symbol e

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