Re: Mathematica integration Vs Sympy

*To*: mathgroup at smc.vnet.net*Subject*: [mg130563] Re: Mathematica integration Vs Sympy*From*: Alex Krasnov <akrasnov at eecs.berkeley.edu>*Date*: Sun, 21 Apr 2013 05:16:06 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <20130420094229.B63996A64@smc.vnet.net>

Mathematica's Integrate implicitly assumes that parameters have generic values. The result can be invalid for special values, in this case, a==1. It appears that the same is true for SymPy's integrate, as u.subs({a:1}) demonstrates. For other values, the Mathematica and SymPy results appear to differ by a constant of integration. Both results are valid. This is a consequence of different integration procedures and can occur even for the same integral in different forms in Mathematica and presumably SymPy. Alex On Sat, 20 Apr 2013, Sergio R wrote: > Hello all, > > Just for fun a put an integral I was doing via mathematica > WolframAlpha > [ http://www.wolframalpha.com/input/?i=Integrate[1%2F%28x*%281-a*%281-x%29%29%29%2Cx] > ] > into the online sympy [ http://live.sympy.org/ ] console > the following: > > a = Symbol('a'); g = 1/(x*(1-a*(1-x))) ; u=simplify(integrate(g,x)) > > Then, to display the result, at the sympy ">>>" prompt, type u > and hit return. > > To my surprise, sympy seems to give the right result without any > assumption, while mathematica's result seems to assume a>1, which is > not specified. Also for this case (a>1) sympy gives an extra constant > which is not present in the mathematica result. > > Is there a way to make mathematica to output a general result like > sympy > in this case? > > Sergio >

**References**:**Mathematica integration Vs Sympy***From:*Sergio R <sergiorquestion@gmail.com>