Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2005
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2005

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

Search the Archive

Re: Making a new definition of Equal work with lists as well

  • To: mathgroup at smc.vnet.net
  • Subject: [mg63387] Re: Making a new definition of Equal work with lists as well
  • From: "dan.bernstein at gmail.com" <dan.bernstein at gmail.com>
  • Date: Wed, 28 Dec 2005 03:55:43 -0500 (EST)
  • References: <dor2jc$alo$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Thank you, Bill and Jean-Marc, for your replies.

I'm afraid I didn't give a sufficiently general example in my question.
What I would like to do is to be able to get True/False results for
expressions as general as

{CL[2,3], 5, {CL[4,5], CL[2,2]}, x} == {CL[2,3], 8, {CL[6,7], CL[9,9]},
y}

that is, lists containing both CLs and other elements, and nested lists
etc.

Making Equal listable wouldn't work because I would then get also a
list (of booleans) as a result.

I think defining Equal for CL[a_, b_] could have "just worked" if Equal
for lists was internally defined to AND the Equal of all matching
pairs, something like

Equal[j_ListQ, k_ListQ]:=If[Length[j]!=Length[k], False,
And@@Table[Equal[j[[i]], k[[i]]], {i, 1, Length[j]}]

And I guess I could re-define it this way, but I wonder what the
built-in definition is, and what I stand to lose by overriding it like
that.

Thanks again,
-- Dan


  • Prev by Date: Re: Re: Questions regarding MatrixExp, and its usage
  • Next by Date: Re: preparing multiple choice questions
  • Previous by thread: Re: Making a new definition of Equal work with lists as well
  • Next by thread: Re: Re: Making a new definition of Equal work with lists as well