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## [Axiom-developer] [#180 bug #9216 differentiating sums with respect to a

**From**: |
kratt6 |

**Subject**: |
[Axiom-developer] [#180 bug #9216 differentiating sums with respect to a bound is wrong] Old Discussion |

**Date**: |
Thu, 23 Jun 2005 03:28:25 -0500 |

Changes
http://page.axiom-developer.org/zope/mathaction/180Bug9216DifferentiatingSumsWithRespectToABoundIsWrong/diff
--
>* > > #3148: bug #9216 differentiating sums with respect to a *
>* > bound is wrong [A]*
>* > *
>* > in my opinion correct beyond doubt.*
>* *
>* In the patch report you wrote:*
>* *
>* "Mathematically axiom produces correct output now, however*
>* I'm not sure whether my patch is best possible.*
>* *
>* Maybe there should be a function D in OutputForm that displays*
>* unevaluated differentiation. Also, I find it ugly to use the*
>* raw %diff operator in COMBF. Furthermore, is it necessary to*
>* substitute a dummy variable for the variable of differentiation?"*
>* *
>* I am concerned that this is another case of a "quick fix" for*
>* which we should consider a more general solution of the kind*
>* that you suggest above.*
In this case the situation is a tiny little bit different, since here also
Axioms internal representation is wrong. Worse: the design of Axioms Algebra
currently doesn't provide "unevaluated differentiation". Obviously, it was
thought that anything can be differentiated. In fact, I'm almost sure that
attempting to differentiate a sum by one of its bound should signal an error,
because it is impossible to assign a mathematically correct meaning to it. In
this sense, I'd suggest that we aim to reach consensus until end of January.
--
forwarded from http://page.axiom-developer.org/zope/mathaction/address@hidden

**[Axiom-developer] [#180 bug #9216 differentiating sums with respect to a bound is wrong] Old Discussion**,
*kratt6* **<=**