Working with D, definition of a function

*To*: mathgroup at smc.vnet.net*Subject*: [mg75912] Working with D, definition of a function*From*: "Thomas Schmelzer" <thomas.??? at balliol.ox.ac.uk>*Date*: Sun, 13 May 2007 05:46:53 -0400 (EDT)*Organization*: Balliol College*Reply-to*: "Thomas Schmelzer" <thomas.??? at balliol.ox.ac.uk>

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