Re: Trig Simplifications
- To: mathgroup at smc.vnet.net
- Subject: [mg3704] Re: Trig Simplifications
- From: hohmuth at cipserv1.physik.uni-ulm.de (Lars Hohmuth)
- Date: Wed, 10 Apr 1996 02:10:51 -0400
- Organization: Uni Ulm
- Sender: owner-wri-mathgroup at wolfram.com
In article <4ka54g$sai at dragonfly.wolfram.com> Alexander Casti <arc at carmen.phys.columbia.edu> writes:
>From: Alexander Casti <arc at carmen.phys.columbia.edu>
To: mathgroup at smc.vnet.net
>Subject: Trig Simplifications
>Date: 8 Apr 1996 04:36:32 GMT
>Basically my question is how to get mathematica to write
>Exp[I x] in place of Cos[x] + I Sin[x]
>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]
>I tried the substitution command
>In[2]: % ./ Cos[X]+I Sin[X]-> Exp[I X] and it returned
>Out[2]: E^{I X} - Cos[2 X] + I Sin[2 X]
>So, it seems as though this simple minded approach is not
>enough for mathematica to understand the substitution rules
>for powers of complex exponentials other than the one I
>explicitly gave.
>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 ?
>Thanks for your time.
>Alex
If you have the Trigonometry package loaded, try the command
TrigToComplex[Cos[x] + I Sin[x]].
CU,
Lars
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