Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » Software » comp.soft-sys.math.mathematica

Topic: Re:[mg4144]More "Logical" functions?
Replies: 0  

Advanced Search

Back to Topic List Back to Topic List  
Edward G. Neuman

Posts: 13
Registered: 12/7/04
Re:[mg4144]More "Logical" functions?
Posted: Jun 16, 1996 2:13 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

Scott Herod wrote:

>I often find myself trying to solve big sets of polynomial equations.
>I realize that there are Groebner basis packages for use in this but
>many times I can get by with Reduce and Solve. My problem is this:
>
>Often I get results like
>
> {{ x -> 0 }, {x -> 0, y -> 5 }, {x -> 0, z -> -2}, ... }
>
>where {x -> 0} is common to all of the terms. I would like to be able
>to factor out the x=0 from each equation. I don't need to see everything
>else if x has to be zero anyway.
>
>Currently I'm doing a LogicalExpand[results && x != 0] to see the cases
>where x does not have to be zero, but something to factor the x -> 0
>would be nicer.
>
>Does anyone know of an existing package do Logical expression operations?
>
>Scott Herod
>(sherod@newton.colorado.edu)
>
>
>


To delete from your list expressions like x->c, where c is a number, you can
use the rewrite-rule capability of Mathematica:

a={{x->0},{x->0,y->5},{x->1,y->0}};
rule1=#/.{x->c_,y___}->{y}&;
a//rule1
{{}, {y -> 5}, {y -> 0}}

===============================================================================
Edward Neuman Phone: (618) 453-6501
Department of Mathematics Fax: (618) 453-5300
Southern Illinois University E-mail: edneuman@math.siu.edu
Carbondale, Ill. 62901-4408
WWW: http://www.science.siu.edu/mathematics/neuman/








Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.