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Re: Simple indefinite integral disagrees with table

  • To: mathgroup at smc.vnet.net
  • Subject: [mg28663] Re: [mg28647] Simple indefinite integral disagrees with table
  • From: Matt.Johnson at autolivasp.com
  • Date: Sat, 5 May 2001 04:00:47 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Mitch-

Use the correct mathematica notation, it agrees with the CRC answer:

In[6]:=
mitchIntegral = Integrate[xx Cos[aa xx], xx]
Out[6]=
\!\(Cos[aa\ xx]\/aa\^2 + \(xx\ Sin[aa\ xx]\)\/aa\)
In[7]:=
crcAnswer = (1/aa^2) Cos[aa xx] + (xx/aa) Sin[aa xx];
mitchIntegral == crcAnswer
Out[8]=
True

Your input uses Cos as a variable, not a call to the cosine function.  Read
the book, learn about the brackets....

-matt






"Mitch Berkson" <berkson at home.com> on 05/03/2001 10:23:11 PM

cc:
Subject: [mg28663]  [mg28647] Simple indefinite integral disagrees with table



The Mathematica solution to the indefinite integral below doesn't agree
with
that found in my CRC tables.

Integrate[xx Cos (aa xx), xx]
= (1/3) aa Cos xx^3

The CRC table gives: (1/aa^2) Cos (aa xx) + (xx/aa) Sin (aa xx)

The Mathematica solution doesn't look right.  Thanks for any help.

Mitch Berkson





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