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Re:[mg4144]More "Logical" functions?
Posted:
Jun 16, 1996 2:13 AM


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 rewriterule 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) 4536501 Department of Mathematics Fax: (618) 4535300 Southern Illinois University Email: edneuman@math.siu.edu Carbondale, Ill. 629014408 WWW: http://www.science.siu.edu/mathematics/neuman/



