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Math Forum » Discussions » Software » comp.soft-sys.math.mathematica

Topic: ComplexExpand off by a factor of (-1)?
Replies: 3   Last Post: Feb 23, 2013 7:01 AM

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Murray Eisenberg

Posts: 2,030
Registered: 12/6/04
Re: ComplexExpand off by a factor of (-1)?
Posted: Feb 23, 2013 7:01 AM
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Hint: in your expression, replace 2*I by 2*k and you'll see why Mathematica gave you the correct value, i.e., exactly what you asked for!
On Feb 22, 2013, at 1:05 AM, charles.ces@gmail.com wrote:

> Would someone be able to help me understand why when I enter the expression:
>
> ComplexExpand[(E^(I*y) - E^(-I*y))/2*I] I get a result of -Sin[y] instead of Sin[y]?
>
> Thanks.
>
> Charles S.

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Murray Eisenberg murray@math.umass.edu
Mathematics & Statistics Dept.
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