Re: Extract coefficients of a trig polynomial

*To*: mathgroup at smc.vnet.net*Subject*: [mg126146] Re: Extract coefficients of a trig polynomial*From*: Yi Wang <tririverwangyi at gmail.com>*Date*: Fri, 20 Apr 2012 07:49:48 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <jmoge7$46g$1@smc.vnet.net>

Hi, Sam, The following may help. But it may be not as general as you want. Coefficient[expr, #] & /@ {Cos[2 \[Theta]], Cos[4 \[Theta]], Cos[6 \[Theta]]}