Re: differentiate a function of a function

*To*: mathgroup at smc.vnet.net*Subject*: [mg75090] Re: [mg75071] differentiate a function of a function*From*: "Chris Chiasson" <chris at chiasson.name>*Date*: Mon, 16 Apr 2007 20:17:36 -0400 (EDT)*References*: <200704160813.EAA09826@smc.vnet.net>

f[x_, y_] = Tan[t[x, y] + a[x, y]] D[f[x, y], x]*Fold[D, f[x, y], {x, y}] == 8 // Simplify ?? On 4/16/07, kem <kemelmi at gmail.com> wrote: > Hi, > > I was wondering how do I define a function in mathematica to be able > to differentiate it etc, where some of the parameters of this function > should be also a function. For example I want to be able to do the > following operations: > > 1) to say that f is a function: f(x,y) = Tan[t(x,y)+a(x,y)] > > 2) take D[f,x] , such that also t(x,y) and a(x,y) will be also > differentiated > > 3) be able to substitute these into some equation like: f_x f_xy = 8 > > Thanks a lot > > kem > > > -- http://chris.chiasson.name/

**References**:**differentiate a function of a function***From:*"kem" <kemelmi@gmail.com>