Re: Working with D, definition of a function

*To*: mathgroup at smc.vnet.net*Subject*: [mg75975] Re: Working with D, definition of a function*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Mon, 14 May 2007 03:42:59 -0400 (EDT)*References*: <f26nfr$450$1@smc.vnet.net>

Hi, you mean ComPath[w_, mu_, bias_] := mu*(\[ImaginaryI]*w + 1) 2 + bias; ComPathPrime[w_, mu_] = D[ComPath[w, mu, 0], w] notice the Set[] insead of your SetDelayed[] Regards Jens Thomas Schmelzer wrote: > Hi, > > I have defined a map > > ComPath[w_, mu_, bias_] := mu*(\[ImaginaryI]*w + 1)^2 + bias; > Now, I would like to use the derivative with respect to w as a further > function. > > D[ComPath[w, mu, 0], w] > > gives the answer I expect, but > > ComPathPrime[w_, mu_] := D[ComPath[w, mu, 0], w]; > > doesn't seem to make sense > > ComPathPrime[2, 1] > > results in > > General::ivar : 2 is not a valid variable. > > > > If it seems I have a lack of knowledge about the internals of Mathmatica - > that's right. > > Can you briefly explain why this should not work? > > Best, > > Thomas > > > > > > > > > > > >