See https://github.com/sympy/sympy/issues/11017. It would be nice if we
could fix ratint to not flip signs in the logarithm.

Aaron Meurer

On Mon, Sep 19, 2016 at 2:43 AM, Kalevi Suominen <jks...@gmail.com> wrote:

>
> There are several integrators in SymPy. The latter form is produced by
> ratint.
>
> >>> from sympy.integrals.rationaltools import ratint
> >>> from sympy.abc import t
> >>> ratint(1/(4*(-t + 4)), t)
> -log(t - 4)/4
>
> Kalevi Suominen
>
>
> On Monday, September 19, 2016 at 5:06:22 AM UTC+3, Raphael Timbó wrote:
>>
>> Since the images with the results are distorted:
>>
>> First result:
>>
>> -(1/4)*log(4*t - 16)
>>
>> Results given by the step-by=step solution on sympy gamma:
>>
>> -(1/4)*log(-t + 4)
>>
>>
>>
>> On Sunday, September 18, 2016 at 3:18:31 PM UTC-3, Raphael Timbó wrote:
>>>
>>> Hi,
>>> I was trying to use:
>>> integrate(Rational(1,4)*(1/(4-t)))
>>>
>>> This was returning:
>>> −14log(4t−16)
>>>
>>> I was not expecting this result... I went to sympy gamma to see the
>>> steps and I saw that:
>>>
>>> Antiderivative forms:
>>> <http://gamma.sympy.org/input/?i=integrate%28Rational%281%2C4%29*%281%2F%284-t%29%29%29#integral_alternate_fake>
>>>
>>>    - integrate(1/(4*(-t + 4)), t)
>>>    −14log(4t−16)
>>>
>>>
>>> But when you check the steps you have:
>>>
>>> The answer is:
>>>
>>> −14log(−t+4)+constant
>>>
>>>
>>>
>>>
>>>
>>> I could not understand why the results are different...
>>> Any explanation?
>>>
>>> Thank you!
>>>
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