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Re: Logical evaluation

  • To: mathgroup at
  • Subject: [mg82326] Re: Logical evaluation
  • From: Bill Rowe <readnewsciv at>
  • Date: Wed, 17 Oct 2007 04:14:39 -0400 (EDT)

On 10/16/07 at 3:27 AM, mmandelberg at (Michael Mandelberg)

>I can't figure out why the following does not evaulate to TRUE:

>In[100]:= \[ExponentialE]^(-\[ImaginaryI] x) + \[ExponentialE]^(\
>\[ImaginaryI] x) == 2 TrigToExp[Cos[x]]

>Out[100]= \[ExponentialE]^(-\[ImaginaryI] x) + \[ExponentialE]^(\
>\[ImaginaryI] x) ==
>2 (\[ExponentialE]^(-\[ImaginaryI] x)/ 2 +
>\[ExponentialE]^(\[ImaginaryI] x)/2)

>Any ideas?

Use Simplify, i.e.,

In[9]:= E^((-I)*x) + E^(I*x) == 2*TrigToExp[Cos[x]] // Simplify

Out[9]= True

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