Author 
Comment/Response 

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 ?
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