Re: Periodic function Roots

*To*: mathgroup at smc.vnet.net*Subject*: [mg58401] Re: Periodic function Roots*From*: dh <dh at metrohm.ch>*Date*: Fri, 1 Jul 2005 02:01:54 -0400 (EDT)*References*: <da0bka$fkj$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, do I understand your question right? You want to get expansion coefficients A,B,.. in a cosine expansion of the periodic function K. Toward this aim, there is: Calculus`FourierTransform`FourierCosCoefficient here is an example: Let K= Mod[t^2,2 Pi] then we get the n-th expansion coefficient by: FourierCosCoefficient[Mod[t^2, 2Pi], t, n] the first few are: {1/12, -Pi^(-2), 1/(4*Pi^2), -1/(9*Pi^2)} sincerely, Daniel FBellas wrote: > Hello, I'm trying to solve an periodic ecuation involving several harmonics > (Style ACos(x)+BCos(2x)+...==K). Mathematica can't let me us 'Solve' > function, so it gives me the error: > Solve::tdep: The equations appear to involve the variables to be solved for > \ > in an essentially non-algebraic way. > > To arrange this, i'm making a little program involving FindRoot function to > find at least two roots from the ecuation in the first period. But I would > like to know if there are some other method to do this more easily. > > Thanks a lot > > F. Bellas > > > > > >