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Assumptions in Integrate


Dear Math Group,

	I find the results of using assumptions in Integrate somewhat
stranege. For instance,

In[21]:= Integrate[Cos[n x], {x, -Pi, Pi}]

Out[21]= 2 Sin[n Pi]
	 -----------
    	     n

In[22]:= Integrate[Cos[n x], {x, -Pi, Pi}, 
		   Assumptions -> Element[n, Integers]]

Out[22]=
            2
2 Sin[Sqrt[n ] Pi]
------------------
           2
     Sqrt[n ]

In[23]:= $Version

Out[23]= "4.0 for Power Macintosh (July 20, 1999)"

	I know I can define my own transformation rules, but one would
think that Mathematica should do it directly.

Julian Aguirre			| Voice:  +34 946012659
Departamento de Matematicas	| Fax:    +34 944648500
Universidad del Pais Vasco	| Postal: Aptdo. 644, 48080 Bilbao, Spain
				| email:  mtpagesj at lg.ehu.es



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