Re: ComplexExpand off by a factor of (-1)?

*To*: mathgroup at smc.vnet.net*Subject*: [mg129894] Re: ComplexExpand off by a factor of (-1)?*From*: Raul Martinez <raulmart at mac.com>*Date*: Sat, 23 Feb 2013 07:03:06 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <20130222060524.703B768D0@smc.vnet.net>

The reason is that the denominator should be (2*I) instead of 2*I. As it stands, the expression (E^(I*y) - E^(-I*y))/2*I is interpreted as I*(E^(I*y) - E^(-I*y))/2. Raul On Feb 21, 2013, at 10:05 PM, charles.ces at 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. >

**References**:**ComplexExpand off by a factor of (-1)?***From:*charles.ces@gmail.com