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MathGroup Archive 1990

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Integrate?

  • To: "mathgroup" <mathgroup at yoda.ncsa.uiuc.edu>
  • Subject: Integrate?
  • From: "WILLIAM M. GOLDING" <golding at ccf4.nrl.navy.mil>
  • Date: 6 Nov 90 22:00:00 EST

		In a previous posting concerning this integration
flaw in Mathematica which Robert Staerk recently brought up,

	Integrate[Sqrt[2-2 Cos[x]],{x,0,2 Pi}]  =?= 0

Jeffrey Golden  mentions an integral which he has just been able
to get Macsyma to do correctly. The integral he mentions is

	Integrate[Sqrt[x + 1/x -2],{x,0,1}] = 4/3  .

Jeff says that Macsyma used to give the result as -4/3, which by the
way is what Mathematica gives. I just wanted to point out the similarity
between these two integrals. If in the second integral x is replaced by
E^(I x) the first integral is almost obtained except for a phase factor
and for the integration contour which I don't quite know how to interpret
at the moment. Anyways I just thought I'd mention the connection
since Jeff implied that the second form has been corrected in Macsyma.


					Mike Golding
					Email golding at ccf.nrl.navy.mil





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