Changes
http://wiki.axiom-developer.org/212SubstitutingForAnOperatorInASumDoesNotApplyTheSummationAlgorithms/diff
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??changed:
-
-
-From BillPage Mon Oct 3 01:08:57 -0500 2005
-From: Bill Page
-Date: Mon, 03 Oct 2005 01:08:57 -0500
-Subject: (new) substituting for an operator in a sum does not apply the
- summation algorithms
-Message-ID: <[EMAIL PROTECTED]>
-
-
-Update of bug #9217 (project axiom):
-
- Status: None => transferred
- Internal cause: first the sum is evaluated. Since the argument --
-f(x)-- is not a polynomial or rational function, using first iidsum, than
-idsum of COMBF. Afterwards the substitution is performed. Now the sum has the
-internal format
-%defsum [%A, %A, i, a, b], which is again evaluated with iidsum and idsum of
-COMBF. The function sum$InnerPolySum is never called, of course. A general
Original Savannah bug 9217
Summary:
Although axiom can evaluate this sum, it does not.
Example of code trigerring the bug:
\begin{axiom}
f := operator 'f
sum(f(i),i=a..b)
eval(%,f,x+->x)
\end{axiom}
Internal Cause
first the sum is evaluated. Since the argument 'f(x)' is not a polynomial
or rational function, using first iidsum, than idsum of COMBF. Afterwards
the substitution is performed. Now the sum has the internal format
'%defsum [%A, %A, i, a, b]', which is again evaluated with iidsum and idsum of
COMBF. The function 'sum$InnerPolySum' is never called, of course. A general
??changed:
-the time to check) => first the sum is evaluated. Since the argument --
-f(x)-- is not a polynomial or rational function, using first iidsum, than
-idsum of COMBF. Afterwards the substitution is performed. Now the sum has the
-internal format
-%defsum [%A, %A, i, a, b], which is again evaluated with iidsum and idsum of
-COMBF. The function sum$InnerPolySum is never called, of course. A general
-solution is to call sum from within idsum, but in this case, care has to be
-taken that summation algorithms that can fail (such as Gosper's) do not
-produce an infinite loop. (In fact I think this is OK, I only did not have
-the time to check)
-
-
- _______________________________________________________
-
-Reply to this item at:
-
- <http://savannah.nongnu.org/bugs/?func=detailitem&item_id=9217>
-
-_______________________________________________
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the time to check)
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