Re: Eliminating Annoying Minus Signs
- To: mathgroup at smc.vnet.net
- Subject: [mg58770] Re: [mg58756] Eliminating Annoying Minus Signs
- From: yehuda ben-shimol <bsyehuda at gmail.com>
- Date: Sun, 17 Jul 2005 13:03:15 -0400 (EDT)
- References: <76e8f81805071705503c70daa4@mail.gmail.com> <NDBBJGNHKLMPLILOIPPOIEHEEJAA.djmp@earthlink.net>
- Reply-to: yehuda ben-shimol <bsyehuda at gmail.com>
- Sender: owner-wri-mathgroup at wolfram.com
Hi David,
Although not documented it seems that both Numerator and Denominator
are listable so
(-Numerator[#])/(-Denominator[#])&[test]
or
test//(-Numerator[#])/(-Denominator[#])&
will do the same without mapping.
yehuda
On 7/17/05, David Park <djmp at earthlink.net> wrote:
> Yehuda,
>
> Thanks. That seems pretty good.
>
> We could turn this into a routine that could be mapped onto terms more
> generally in an expression.
>
> NDSignSwitch = (-Numerator[#])/(-Denominator[#]) &;
>
> test = {-((2*x)/(-1 + z)), -((2*y)/(-1 + z)), -1};
>
> NDSignSwitch /@ test
> {(2*x)/(1 - z), (2*y)/(1 - z), -1}
>
> David Park
> djmp at earthlink.net
> http://home.earthlink.net/~djmp/
>
>
>
> From: yehuda ben-shimol [mailto:bsyehuda at gmail.com]
To: mathgroup at smc.vnet.net
>
> Hi David,
> How about
> (- Numerator /@ test)/(- Denominator /@ test)
> this is not error prone.
> I'm almost certaint that there is more efficient way of doing this.
> I'll try to find it later
> regards
> yehuda
>
>