Status: Accepted
Owner: smichr
Labels: Type-Defect Priority-Medium
New issue 2047 by smichr: subs_atoms should omit more variables when doing
subs in Integral
http://code.google.com/p/sympy/issues/detail?id=2047
Since more than one atom can be passed to subs_atoms, care must be taken
that all variables of integration are removed before beginning the
substitution.
Integral(x, (x, 1, y), (y, 1, 2)).subs({x:1, y:2}).doit()
3/2
Integral(x, (x, 1, y), (y, 1, 2)).doit()
2/3
Since y and x are dummy variables, neither of them should have been
replaced with the substitution.
The use of commit 1823 (t2 branch) can help in such situations by telling
what variables are truly variable in the Integral:
Integral(x, (x, 1, y), (y, 1, 2)).symbols
set([])
This means that there are not surviving symbols in the integral and thre is
no substitution that should take place.
In addition, if there are no limits then a request to change variables
should trigger a call to Integral.transform since now the integral of
integration is also going to be the final variable in the integral.
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