Re: Replacement gyrations
- To: mathgroup at smc.vnet.net
- Subject: [mg55892] Re: [mg55872] Replacement gyrations
- From: DrBob <drbob at bigfoot.com>
- Date: Sat, 9 Apr 2005 03:55:32 -0400 (EDT)
- References: <200504080537.BAA25184@smc.vnet.net>
- Reply-to: drbob at bigfoot.com
- Sender: owner-wri-mathgroup at wolfram.com
Wsol /. a_/b_ :> a/Factor@b
{{W11 -> (A2*x21 + A1*x32)/
(L86^2*((-x32)*y21 +
x21*y32)), W12 ->
-((A2*y21 + A1*y32)/
(L86^2*(x32*y21 -
x21*y32))),
W21 -> (A2*x21 + A1*x32)/
(L75^2*((-x32)*y21 +
x21*y32)), W22 ->
-((A2*y21 + A1*y32)/
(L75^2*(x32*y21 -
x21*y32)))}}
or just:
Simplify@Wsol
{{W11 -> (A2*x21 + A1*x32)/
(L86^2*((-x32)*y21 +
x21*y32)), W12 ->
-((A2*y21 + A1*y32)/
(L86^2*(x32*y21 -
x21*y32))),
W21 -> (A2*x21 + A1*x32)/
(L75^2*((-x32)*y21 +
x21*y32)), W22 ->
-((A2*y21 + A1*y32)/
(L75^2*(x32*y21 -
x21*y32)))}}
Bobby
On Fri, 8 Apr 2005 01:37:00 -0400 (EDT), <carlos at colorado.edu> wrote:
> A Solve for 4 variables W11,W12,W21,W22 produces, after Simplify
>
> Wsol={{W11 -> (A2*x21 + A1*x32)/(L86^2*(-(x32*y21) + x21*y32)),
> W12 -> (A2*y21 + A1*y32)/(-(L86^2*x32*y21) + L86^2*x21*y32),
> W21 -> (A2*x21 + A1*x32)/(L75^2*(-(x32*y21) + x21*y32)),
> W22 -> (A2*y21 + A1*y32)/(-(L75^2*x32*y21) + L75^2*x21*y32)}}
>
> Question 1: why do L86^2 and L75^2 come out as a factor in two
> expression denominators and not in the others? Seems a random event.
>
> This uncertainty inhibits the action of further replacement rules such
> as
> (-(x32*y21) + x21*y32) -> 2*A123
>
> which works on W11 and W21 only.
>
> Question 2: I tried Collect [Wsol,{L86,L75}] to try to force grouping
> of L86^2 and L75^2, but it has no effect.
> Do I need to say Wsol=Wsol*L86^2*L75^2, Simplify, replace and finally
> Wsol=Wsol/L86^2*L75^2 ? Or fool around with Numerator and Denominator?
>
>
>
>
--
DrBob at bigfoot.com
- References:
- Replacement gyrations
- From: carlos@colorado.edu
- Replacement gyrations