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Sign Declaration

• To: mathgroup at smc.vnet.net
• Subject: [mg80028] Sign Declaration
• From: Mr Ajit Sen <senra99 at yahoo.co.uk>
• Date: Sat, 11 Aug 2007 02:02:21 -0400 (EDT)

 Dear MathGroup,

 Given the list  A= {a,b,c,d,e,f,g,h}, I'd like to
tell
 Mathematica (5.2) that a,b,...,e are +ve, and f,g,h are -ve.

 I'm using the following

          Table[Sign[A[[i]]]^=1,{i,5}];

          Table[Sign[A[[i]]]^=-1,{i,6,8}];


 My queries are :

 1. Is it possible to combine the above into 1
Table[]?

 2. How do I achieve the same thing with the construct

              x/:Sign[x]=1
    in Table ?

 3. Any more efficient ways of doing those sign 
    declarations?

  Thanking you in advance.

  Ajit.

    


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• Follow-Ups:
  • Re: Sign Declaration
    • From: Andrzej Kozlowski <akoz@mimuw.edu.pl>