Re: Bug in Reduce?

*To*: mathgroup at smc.vnet.net*Subject*: [mg60425] Re: [mg60406] Bug in Reduce?*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Fri, 16 Sep 2005 03:49:05 -0400 (EDT)*Reply-to*: hanlonr at cox.net*Sender*: owner-wri-mathgroup at wolfram.com

$Version 5.2 for Mac OS X (June 20, 2005) Reduce[{a c-b d==0,a d+b c==0}, {a,b,c,d},Reals]//Simplify (a == 0 && b == 0) || (c == 0 && d == 0) Bob Hanlon > > From: "Kennedy" <jack at realmode.com> To: mathgroup at smc.vnet.net > Date: 2005/09/15 Thu AM 05:16:26 EDT > Subject: [mg60425] [mg60406] Bug in Reduce? > > The source of this apparent bug could be my misunderstanding of the middle, > "vars" parameter of Reduce, but it sure seems like the following output > indicates that c must be 0 for my two equations to be satisfied, when in > fact if a and b are both 0, c does not need to be 0. > > Regards, > Jack > > In[1]:= > Reduce[{a c - b d == 0, a d + b c == 0}, {a, b, c, d}, Reals] // > FullSimplify > > Out[1]= > c == 0 && (d == 0 || (a == 0 && b == 0)) > > (version 5.1 for Windows) > >