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RE: Function argument

• To: mathgroup at smc.vnet.net
• Subject: [mg67000] RE: [mg66953] Function argument
• From: "David Park" <djmp at earthlink.net>
• Date: Tue, 6 Jun 2006 06:28:51 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

Bonny,

First, write your definition with patterns and with a SetDelayed.

g[a_, f_] := f[a]

Then you can just supply function names...

g[Pi, Sin]
0

g[a, f]
f[a]

or you can supply pure functions (Look up Function in Help), which act as
function names.

g[1, a#^2 + b# + c &]
a + b + c

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/




From: Bonny [mailto:Banerjee at cse.ohio-state.edu]
To: mathgroup at smc.vnet.net


I would like to define a function g that evaluates another function f at a
given value. That is,

g[a, f[x]] := f[a]

For example, I might want the function f[x]=ax^2+bx+c to be evaluated at x=1
and get the result a+b+c. That is,

g[1, ax^2+bx+c] should evaluate to a+b+c.

Again, I might want the function f[x]=Sin[x] to be evaluated at x=pi and get
the result 0. That is,

g[pi, Sin[x]] should evaluate to 0.

Is there a way to accomplish this in Mathematica? Any help would be
appreciated.

Thanks,
Bonny.