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Re: Trig Simplifications

  • To: mathgroup at smc.vnet.net
  • Subject: [mg3706] Re: Trig Simplifications
  • From: rhall2 at umbc.edu (hall robert)
  • Date: Wed, 10 Apr 1996 02:11:12 -0400
  • Organization: University of Maryland, Baltimore County
  • Sender: owner-wri-mathgroup at wolfram.com

In article <4ka54g$sai at dragonfly.wolfram.com>,
Alexander Casti  <arc at carmen.phys.columbia.edu> wrote:
>
>Suppose I have the expression  
>
>In[1]: f[x_]= Cos[x] + I Sin[x] - Cos[2 X] + I Sin[2 X]
>
>I would like mathematica to simplify this into
>
>f[x_]= Exp[I X] - Exp[2 I X]
>
>In addition, commands like Simplify[Blah] do not seem to do
>the trick either.  I believe I have the trigonometry package
>loaded in (via the command Needs["Algebra`Trigonometry`"]).
>What must I do ? 

The answer is not in "The Book," and not in "The Other Book,"
but in "The Other Other Book" (Standard Guide to Mathematica
Packages.) Looking in the index under "Complex" gets you directed
to p. 16. Combine the recommended command w/ Simplify to get
In[6]:=
     f[x_]= Cos[x] + I Sin[x] - Cos[2 X] + I Sin[2 X];
     TrigToComplex[ f[ x ] ] // Simplify
Out[7]=
      I x    -2 I X
     E    - E

Neat, huh?
-- 
Bob Hall            | "Know thyself? Absurd direction!
rhall2 at gl.umbc.edu  |  Bubbles bear no introspection."  -Khushhal Khan Khatak

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