#9424: numerical evaluation of symbolic sums
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Reporter: burcin | Owner: burcin
Type: defect | Status: needs_review
Priority: major | Milestone: sage-duplicate/invalid/wontfix
Component: | Resolution:
symbolics | Merged in:
Keywords: | Reviewers:
Authors: | Work issues:
Report Upstream: N/A | Commit:
Branch: | Stopgaps:
Dependencies: |
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Changes (by rws):
* status: new => needs_review
* milestone: sage-6.3 => sage-duplicate/invalid/wontfix
Comment:
Your problem is threefold: 1. you use `n` both as sum endpoint and
variable, 2. Sage `sum` is only intended with symbolic endpoints, and 3.
the need to use Python summation may require defining a Python function
instead of a Sage symbolic function:
{{{
sage: sum?
...
Warning: This function only works with symbolic expressions. To sum any
other objects like list elements or function return values,
please use python summation...
sage: I(n)=sum(abs(y2(p(k))-y1(p(k)))*Delta,k,1,n);
sage: I
n |--> 2*sum(abs(-4*k^2 - 3*(2*k - 1)*n + 3*n^2 + 4*k - 1), k, 1, n)/n^3
sage: def I(n):
....: return (2*sum(abs(-4*k^2 - 3*(2*k - 1)*n + 3*n^2 + 4*k - 1) for
k in range(1,n+1))/n^3)
....:
sage: I(10)
1301/250
sage: [I(i) for i in range(1,11)]
[2, 5, 46/9, 5, 26/5, 277/54, 254/49, 665/128, 418/81, 1301/250]
}}}
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Ticket URL: <http://trac.sagemath.org/ticket/9424#comment:7>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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