Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2007
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2007

[Date Index] [Thread Index] [Author Index]

Search the Archive

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


  • Prev by Date: Re: Re: Curve-fitting/data analysis question...
  • Next by Date: Re: Curve-fitting/data analysis question...
  • Previous by thread: Re: Logical Expression
  • Next by thread: Re: Logical Expression