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Re: Integrate bug

  • To: mathgroup at
  • Subject: Re: Integrate bug
  • From: dooley at goldengatesparc.Berkeley.EDU (Sam Dooley)
  • Date: Mon, 25 Feb 91 09:53:53 PST

Mathematica's formulation of the anti-derivative involves
the Log function, and the direct substitution chose the
wrong branch.  Applying the transformation Log[Exp[x]] -> x
happens to choose the right branch in this case, but this
will not always be true.

Mathematica (MIPS) 1.2 (November 8, 1989) [With pre-loaded data]
by S. Wolfram, D. Grayson, R. Maeder, H. Cejtin,
   S. Omohundro, D. Ballman and J. Keiper
with I. Rivin and D. Withoff
Copyright 1988,1989 Wolfram Research Inc.
 -- X11 windows graphics initialized --

In[1]:= Integrate[Exp[I x] Cos[x],x]

        -I  2 I x   -I      I x
Out[1]= -- E      + -- Log[E   ]
        4           2

In[2]:= % /. x -> 2 Pi

Out[2]= --

Sam Dooley
dooley at Berkeley.EDU

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