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Re: Getting answer out of a ConditionalExpression[]

  • To: mathgroup at smc.vnet.net
  • Subject: [mg132118] Re: Getting answer out of a ConditionalExpression[]
  • From: Bill Rowe <readnews at sbcglobal.net>
  • Date: Sat, 14 Dec 2013 04:02:59 -0500 (EST)
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  • Delivered-to: l-mathgroup@wolfram.com
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On 12/12/13 at 1:27 AM, roger.bagula at gmail.com (Roger Bagula) wrote:

>I'm interested in getting a plot-able array out of the following:
>Clear[x] Table[Solve[(1 + Exp[I*(n*Pi/6 + x)])*(1 + Exp[-I*(n*Pi/6 +
>x)]) == 1/((1 - Exp[I*n*Pi/6])*(1 - Exp[-I*n*Pi/6])), x], {n,
>1, 11}]

>There are two problems: 1) getting the answers out of the {x ->
>ConditionalExpression[
>1/6 (-\[Pi] + 6 I (-((I \[Pi])/6) + 2 I \[Pi] C[1])), C[1]
>\[Element] Integers]}
>and 2) removing the C[1] terms

>I'm particularly interested in plotting the phase angles with log
>expressions: {x -> ConditionalExpression[
>1/2 (-\[Pi] + 2 I (2 I \[Pi] C[1] + Log[1/4 (-3 - I Sqrt[7])])),
>C[1] \[Element] Integers]}, {x -> ConditionalExpression[ 1/2 (-\[Pi]
>+ 2 I (2 I \[Pi] C[1] + Log[1/4 (-3 + I Sqrt[7])])), C[1] \[Element]
>Integers]}

Extracting the answers from rules of the form

sol=x->ConditionalExpression[...]

can be accomplished by

Assuming[conditions, Simplify[x/.sol]]

The C[1] portion can be eliminated using one of the following
rules and applying it

C[1]->0
C[1]->1
C[1]->Sequence[]

Use the first when C[1] is an additive constant, the second if
C[1] is a multiplicative constant and the third if C[1] appears
in a list or something else where substituting 0 or 1 won't work.




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