Integrate(1/(1-x), x) gives wrong result

[Xu Yang (CowFighting)]

Symja: Integrate(1/(1-x), x) = -log(-1 + x)

But the correct answer is: ∫1/(1-x)dx = -log(1 - x)

Thanks.

[Axel Kramer]

This is probably a problem with the Rubi rules definitions version 4.5

[Xu Yang (CowFighting)]

Thank you for your prompt reply. Are there some ways to solve it?

[Axel Kramer]

If you do this test in the Symja online interface, I think it's no bug, because -1/(-1+x) is equal to 1/(1-x)

>>> Integrate(1/(1-x),x)
-Log(-1+x)

>>> D(-Log(-1+x),x)
-1/(-1+x)

[Xu Yang (CowFighting)]

Thank you for your prompt reply. to some extent, the correct answer of " Integrate(1/(1-x),x) " is -1 * log|1-x| . however, we don't have the abs symbol in the algebraic expression. shall we add the abs symbol in symja result?

[Axel Kramer]

I added the following commits to get the expected result:

for master branch: https://bitbucket.org/axelclk/symja_android_library/commits/6dd29ddcb44b0af83c21d80f7262a062a6856ee0?at=master

for java6 branch: https://bitbucket.org/axelclk/symja_android_library/commits/bde2b28e2d0ea6a4eb981267c22c0b6217f809ce?at=java6

[Xu Yang (CowFighting)]

ok, thanks.