Re: How to extract functions from a list and call them with any argument?

• To: mathgroup at smc.vnet.net
• Subject: [mg65951] Re: [mg65919] How to extract functions from a list and call them with any argument?
• From: "David Park" <djmp at earthlink.net>
• Date: Mon, 24 Apr 2006 06:02:07 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```Dom,

Your list is a list of algebraic expressions and not a list of functions. To
obtain a list of functions use the Mathematica Function or pure function
construction.
(Look up Function in Help.)

funclist = {Sin, #^3 &, Cos[#]^2};

funclist[[1]][t]
Sin[t]

Notice that the t came at the end of the calling expression.

You could turn you original list into functions with the following
statement.

{Sin[x], x^3, Cos[x]^2}
Function /@ (% /. x -> #)

giving...

{Sin[x], x^3, Cos[x]^2}
{Sin[#1] & , #1^3 & , Cos[#1]^2 & }

If the last statement is confusing, look up Map and ReplaceAll in Help. Also
notice that the two forms of the first, Sin, function are equivalent.

David Park

From: dmp55 at sympatico.ca [mailto:dmp55 at sympatico.ca]
To: mathgroup at smc.vnet.net

I have a list of functions, i.e.,

funclist = {Sin[x], x^3, Cos[x]^2}.

I can extract each of the functions, like

In[1]:=funclist[[1]]
Out[1]=Sin[x]

, but I don't know how to call these functions with a general argument.
If I type

In[2]:=funclist[t][[1]]

, I get

Out[2]=t

instead of Sin[t] (or t^3 or Cos[t]^2)

What I would like is to extract a function from the list and to call it
with any argument, as it was defined in a standard way:
f[x_]:=Sin[x].

Dom

```

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