See http://docs.sympy.org/latest/tutorial/simplification.html#powers.
powsimp(expr, force=True) will do what you want.
Aaron Meurer
On Thu, Feb 26, 2015 at 12:18 PM, Paul Royik <distantjob...@gmail.com> wrote:
> I need something more general
>
> On Thursday, February 26, 2015 at 7:50:15 PM UTC+2, John Peterson wrote:
>>
>>
>>
>> On Thursday, February 26, 2015 at 8:32:11 AM UTC-7, Paul Royik wrote:
>>>
>>> What is the best way to convert sqrt(x)*sqrt(x-4) to sqrt(x^2-4x) or
>>> (x^2+5x+4)/sqrt(x)/sqrt(x-4) to (x^2+5x+4)/sqrt(x^2-4x)
>>>
>>> I tried replace, but it doesn't work in second case.
>>
>>
>> Be careful, they aren't equal for all values of x, but subs() will do this
>> if you are willing to be explicit...
>>
>>> #!/usr/bin/env python
>>> from sympy import *
>>> print sympify('(x**2 + 5*x + 4) / sqrt(x) /
>>> sqrt(x-4)').subs(sympify('sqrt(x)*sqrt(x-4)'), sympify('sqrt(x**2 - 4*x)'))
>>
>>
>> Output:
>>
>>> (x**2 + 5*x + 4)/sqrt(x**2 - 4*x)
>>
>>
>
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