Re: Logical Expression
- To: mathgroup at smc.vnet.net
- Subject: [mg73424] Re: [mg73385] Logical Expression
- From: Murray Eisenberg <murray at math.umass.edu>
- Date: Fri, 16 Feb 2007 00:57:38 -0500 (EST)
- Organization: Mathematics & Statistics, Univ. of Mass./Amherst
- References: <200702150956.EAA04579@smc.vnet.net>
- Reply-to: murray at math.umass.edu
Try === (SameQ) and =!= (UnsameQ) instead of == (Equal) and ! (Unequal). Martin Schoenecker wrote: > Common sense tells me that the statement that "something is equal to > zero, and unequal to zero at the same time" is a false statement: > > In[1]:= a == 0 && a != 0 > Out[1]= a\[Equal]0&&a=E2=89=A00 > > In[2]:= LogicalExpand[%] > Out[2]= False > > The same, in my opinion, applies to "something is equal to zero and > greater than zero at the same time". Why doesn't Mathematica think so, > and how to convince it to evaluate the following? > > In[3]:= a == 0 && a > 0 > Out[3]= a\[Equal]0&&a>0 > > In[4]:= LogicalExpand[%] > Out[4]= a\[Equal]0&&a>0 > > > Thanks in advance, > Martin > -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305
- References:
- Logical Expression
- From: Martin Schoenecker <ms_usenet@gmx.de>
- Logical Expression