Re: Extracting free parameters from a Solve result
- To: mathgroup at smc.vnet.net
- Subject: [mg93945] Re: [mg93914] Extracting free parameters from a Solve result
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Sat, 29 Nov 2008 04:31:21 -0500 (EST)
- Reply-to: hanlonr at cox.net
rules = {{W11 -> W44, W12 -> -W34, W13 -> W34,
W14 -> -W23 - W33 + W44, W22 -> W33, W24 -> -W34}};
pars = Variables[Last /@ rules[[1]]]
{W23,W33,W34,W44}
Bob Hanlon
---- carlos at colorado.edu wrote:
=============
In solving a Sylvester matrix equation, Solve is given
18 equations in 10 variables: v= {W11,W12,W13,W14,W22,
W23,W24,W33,W34,W44} It returns
{{W11->W44, W12->-W34, W13->W34,
W14->-W23-W33+W44, W22->W33, W24->-W34}}
How do I extract the 4 variables: W44,W34,W23,W33 left
over on the right of the ->, and place them in an ordered list:
pars={W23,W33,W34,W44}
I guess the simplest way would be to Drop the dependent
variables from the v list but the details escape me. Thanks.
--
Bob Hanlon