#14437: rsolve fails with initial conditions
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Reporter: zimmerma | Owner: burcin
Type: defect | Status: new
Priority: minor | Milestone: sage-5.10
Component: calculus | Keywords:
Work issues: | Report Upstream: N/A
Reviewers: | Authors:
Merged in: | Dependencies:
Stopgaps: |
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Consider the following:
{{{
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| Sage Version 5.8, Release Date: 2013-03-15 |
| Type "notebook()" for the browser-based notebook interface. |
| Type "help()" for help. |
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sage: from sympy import Function, Symbol
sage: u = Function('u')
sage: n = Symbol('n', integer=True)
sage: from sympy import rsolve
sage: f = u(n+2) - u(n+1) + u(n)/4
sage: rsolve(f,u(n))
2**(-n)*C0*RisingFactorial(C0/C1 + 1, n)/RisingFactorial(C0/C1, n)
}}}
Since Sage does not know about {{{RisingFactorial}}}, this answer is not
very useful...
Moreover:
{{{
sage: rsolve(f,u(n),{u(0):0,u(1):1})
sage:
}}}
The solution is (computed by Maple 15)
{{{1/4*(8*n+8)*(1/2)^n-2*(1/2)^n}}}.
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14437>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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