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MathGroup Archive 1999

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Re: Re: equaltity of lists

  • To: mathgroup at smc.vnet.net
  • Subject: [mg19147] Re: [mg19092] Re: [mg19036] equaltity of lists
  • From: "Kevin J. McCann" <kevinmccann at Home.com>
  • Date: Thu, 5 Aug 1999 23:58:49 -0400
  • References: <199908050535.BAA03420@smc.vnet.net.>
  • Sender: owner-wri-mathgroup at wolfram.com

Maarten


Agree with you, but then why do you get

Signature[{a,b,c,d}]
True

Signature[{a,b,d,c}]
False

By the same logic this should not return an answer.

Kevin


----- Original Message ----- 
From: <Maarten.vanderBurgt at icos.be>
To: mathgroup at smc.vnet.net
Subject: [mg19147] [mg19092] Re: [mg19036] equaltity of lists


> Drago,
> 
> You should use
> 
> {a, b} === {b, a}
> 
> when you want False as a result.
> 
> The following I copied from the Mathematica help files. This explains the
> difference between '===' and '=='.
> 
> SameQ
> -----
> lhs === rhs yields True if the expression lhs is identical to rhs, and
> yields False otherwise.
> 
> SameQ requires exact correspondence between expressions, except that it
> considers Real numbers equal if their difference is less than the
> uncertainty of either of them.
> 
> 2 === 2. gives False.
> 
> e1 === e2 === e3 gives True if all the ei are identical.
> 
> 
> Equal
> -----
> lhs == rhs returns True if lhs and rhs are identical.
> 
> lhs == rhs is used to represent a symbolic equation, to be manipulated
> using functions like Solve.
> 
> lhs == rhs returns True if lhs and rhs are identical expressions.
> 
> lhs == rhs returns False if lhs and rhs are determined to be unequal by
> comparisons between numbers or other raw data, such as strings.
> 
> Approximate numbers are considered equal if they differ in at most their
> last eight binary digits (roughly their last two decimal digits).
> 
> 2 == 2. gives True.
> 
> e1 == e2 == e3 gives True if all the ei are equal.
> 
> 
> 
> 
> Maarten
> 
> 
> 
> 
> 
> 
> "Drago Ganic" <drago.ganic at in2.hr> on 03-08-99 07:45:05 PM
> 
> 
> Subject: [mg19147] [mg19092]  [mg19036] equaltity of lists
> 
> 
> 
> 
> Hi !!
> 
> Why don't I get an answer (False) when I ask Mathematica
> 
>     {a,b}=={b,a}
> 
> like the one I get with
> 
>     {1,2}=={2,1}
>     False
> 
> Greetings from Croatia,
> Drago Ganic
> 
> 
> 
> 
> 
> 
> 
> 



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