Re: defining a function of functions

*To*: mathgroup at smc.vnet.net*Subject*: [mg110485] Re: defining a function of functions*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Sun, 20 Jun 2010 03:47:04 -0400 (EDT)

innerprod[f_, g_] := Sum[ f[k] Conjugate[g[k]] Part[mylist, k], {k, 1, L}] mylist = Array[c, 5]; L = 3; innerprod[f, g] c[1]*f[1]*Conjugate[g[1]] + c[2]*f[2]*Conjugate[g[2]] + c[3]*f[3]*Conjugate[g[3]] innerprod[f[2, #] &, g] c[1]*f[2, 1]*Conjugate[g[1]] + c[2]*f[2, 2]*Conjugate[g[2]] + c[3]*f[2, 3]*Conjugate[g[3]] Bob Hanlon ---- J Davis <texasautiger at gmail.com> wrote: ============= I want to define an inner product function such as (here mylist is a specified list and L is a specified constant) innerprod[f_, g_] = Sum[f[k]Conjugate[g[k]]Part[mylist,k],{k,1,L}] This works fine but now I need to apply it in a situation where f is a function of 2 variables while g is a function of only one variable, i.e. I want to compute something like the inner product of f[2,n] and g[n]. Of course, I want the ability to freely vary the first input of f. I have accomplish this before rather easily but I'm presently drawing a blank. Thanks for your help. Best, JD