Date: May 28, 2013 3:47 AM
Author: Bob Hanlon
Subject: Re: Through[Divide[f1, f2][x]]

"Sometimes it would be nice to have a "reverse map", that

applied each of a list of functions to a single argument,

instead of a single function to each of a list of arguments."

Use Through

Through[{f1, f2, f3, f4}[x]]

{f1[x], f2[x], f3[x], f4[x]}

or Map

#[x] & /@ {f1, f2, f3, f4}

{f1[x], f2[x], f3[x], f4[x]}

Bob Hanlon

On Sun, May 26, 2013 at 5:06 AM, Ray Koopman <koopman@sfu.ca> wrote:

> Either of these will give you f1[x]/f2[x]:

>

> Divide@@{f1@#,f2@#}&@x

>

> Divide@@(#@x&)/@{f1,f2}

>

> Sometimes it would be nice to have a "reverse map", that

> applied each of a list of functions to a single argument,

> instead of a single function to each of a list of arguments.

>

> ----- Andres Guzman <andres.guzman.fernandez@gmail.com> wrote:

> > $Version

> > 8.0 for Linux x86 (64-bit) (October 10, 2011)

> >

> > Through[Divide[f1, f2][x]]

> > f1[x] (1/f2)[x]

> >

> > (* When what I want is: Divide[f1[x],f2[x]] . An uncomfortable

> > consequence of the way Mathematica treats division.*)

> >

> > Divide[f1, f2] // FullForm

> > Times[f1, Power[f2, -1]]

>

>