Re: Re: Getting the small parts right or wrong. Order and Collect
- To: mathgroup at smc.vnet.net
- Subject: [mg63640] Re: [mg63621] Re: [mg63607] Getting the small parts right or wrong. Order and Collect
- From: "David Park" <djmp at earthlink.net>
- Date: Sun, 8 Jan 2006 03:33:05 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
I think there is Andrzej - if we can use a HoldForm.
expr = (1 + x + y)^3 // Expand;
Fold[Join[#1, List@Cases[expr, #2]] &, {},
{_?(FreeQ[#, x] & ), a_. x, a_. x^2, a_. x^3}];
Collect[(# /. List -> Plus), x] & /@ %;
(HoldForm @@ {%}) /. List -> Plus
(1 + 3*y + 3*y^2 + y^3) + x*(3 + 6*y + 3*y^2) + x^2*(3 + 3*y) + x^3
We get the sequence in the order of the patterns.
David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/
From: Andrzej Kozlowski [mailto:akoz at mimuw.edu.pl]
To: mathgroup at smc.vnet.net
Of course there is no way to make the powers of x ascend as you
originally seems to have wanted but then we can't have everything
even where Mathematica is concerned.
Andrzej Kozlowski