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Student Support Forum: 'Some mis-behaviours' topicStudent Support Forum > General > "Some mis-behaviours"

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Éric Brunet
12/13/99 09:24am


I have just bought mathematica 4.0, and I would like to suggest some minor improvements for future versions. I understand that there are many ways do go around the ``problems'' I present, but I still think that the
default behavior could be nicer.

* Simplify[ Gamma[n+1], Element[n, Integers] ]

I think that this should get simplified into n!

* Series[x,{x,Infinity,0}]

while correct, the result looks ridiculous.

* s=Series[ Exp[ -t x], {x,0,4}]
Integrate[ s Exp[-t],{t,0,Infinity}]

doesn't work. (It says: Limit::''nonopt'':
      ''Options expected (instead of #4) beyond          position 2 in Limit[#1, #2, #3, #4].
An option must be a rule or a list of             rules.'')

On the other hand, if I enter

i=Integrate[ s Exp[-t],{t,0,A}]
Limit[i,A->Infinity],

I get the result expected.

* I want to define a linear operator A on functions

A[f_ + g_] := A[f] + A[g]
....
D[A[f_],d__] ^:= A[ D[f,d] ]

Now this works If I do

D[ A[ Exp[t x] ] , {t,3}]

But doesn't give the expected result if I ask for

Series[ A[ Exp[t x] ], {t,0,3}]

Isn't the operator D used for Series ?

Éric Brunet







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Subject (listing for 'Some mis-behaviours')
Author Date Posted
Some mis-behaviours Éric Brunet 12/13/99 09:24am
Re: Some mis-behaviours Aaron Honecker 12/14/99 3:14pm
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