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Issue 2943: rsolve: wrong result
2 people starred this issue and may be notified of changes. Back to list
Status:  Fixed
Owner:  ----
Closed:  Feb 2013

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Project Member Reported by krastano...@gmail.com, Dec 24, 2011
Not necessarily wrong, but trivial.

sympy:

In [16]: rsolve(a*f(n+1)-b**2*f(n)-f(n+2), f(n), {2:a**2-b**2, 3:a**3-2*a*b**2})
Out[16]: 0

or the same system written differently

In [18]: rsolve(a*f(n-1)-b**2*f(n-2)-f(n), f(n), {2:a**2-b**2, 1:a})
Out[18]: 0

mathematica:

http://www.wolframalpha.com/input/?i=RSolve[{d[n]+%3D%3D+a+d[n+-+1]+-+b^2+d[n-2]%2C+d[1]+%3D%3D+a%2C+d[2]+%3D%3D+a^2+-+b^2}%2C+d[n]%2C+n]
Mar 20, 2012
Project Member #1 asmeurer@gmail.com
(No comment was entered for this change.)
Status: Valid
Oct 29, 2012
Project Member #2 asmeurer@gmail.com
Also 

>>> x = Function('x')
>>> a, k = symbols("a k")
>>> rsolve(Eq(x(k + 1), a*x(k)), x(k))
0
Feb 8, 2013
Project Member #4 asmeurer@gmail.com
That was merged.
Status: Fixed
Mar 5, 2014
Project Member #5 asmeurer@gmail.com
We have moved issues to GitHub https://github.com/sympy/sympy/issues. 
Labels: Restrict-AddIssueComment-Commit
Apr 6, 2014
Project Member #6 skirpic...@gmail.com
Migrated to http://github.com/sympy/sympy/issues/6042
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