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Re: Re: Re: equaltity of lists
*To*: mathgroup at smc.vnet.net
*Subject*: [mg19175] Re: [mg19147] Re: [mg19092] Re: [mg19036] equaltity of lists
*From*: Maarten.vanderBurgt at icos.be
*Date*: Tue, 10 Aug 1999 02:52:40 -0400
*Sender*: owner-wri-mathgroup at wolfram.com
Kevin,
Maybe I do not understand your remark completely. But when I do this on my
PC (Mathematica 4.0) I get
In[1] := Signature[{a, b, c, d}]
Out[1] = 1
In[2] := Signature[{a, b, d, c}]
Out[2] = -1
Which is completely in line with the definition of Signature.
Canonical order has nothing to do with sameness or equality.
Maarten
"Kevin J. McCann" <kevinmccann at Home.com> on 06-08-99 05:58:49 AM
Subject: [mg19175] [mg19147] Re: [mg19092] Re: [mg19036] equaltity of lists
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: [mg19175] [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: [mg19175] [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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