Re: Maximize with Integer constraints

*To*: mathgroup at smc.vnet.net*Subject*: [mg78270] Re: Maximize with Integer constraints*From*: dh <dh at metrohm.ch>*Date*: Wed, 27 Jun 2007 05:29:12 -0400 (EDT)*References*: <f5qjmd$669$1@smc.vnet.net>

Hi, that's a BUG! Wolfram should take note. Mathematica screws up if you give real constrains for integers. Consider: Maximize[{x,0<=x<=2},{x},Integers] gives {2,{x->2}} Maximize[{x,0<=x<=2.},{x},Integers]gives {0.,{x->0}} hope this helps, Daniel sdw wrote: > given entry #1: > > > Maximize[ > {x1 + x2 + x3 + x4, > Element[x1 | x2 | x3 | x4 , Integers] && > 0 <= x1 <= 5.6 && > 0 <= x2 <= 8.6 && > 0 <= x3 <= 9.7 && > 4.0 <= x4 <= 22.4 }, {x1, x2, x3, x4}] > > {4., {x1 -> 0, x2 -> 0, x3 -> 0, x4 -> 4}} > > note - zeros for answers > entry #2: > Maximize[ > {x1 + x2 + x3 + x4, > Element[x1 | x2 | x3 | x4 , Integers] && > 0 <= x1 <= 5.6 && > 0 <= x2 <= 8.6 && > 0 <= x3 <= 9.7 && > 4.1 <= x4 <= 22.4 }, {x1, x2, x3, x4}] > > {44., {x1 -> 5, x2 -> 8, x3 -> 9, x4 -> 22}} > > note good answers... > only difference is 4.1 vs. 4 in constraints > any ideas what is going on? > > thanks, > > sdw > >