Re: More /.{I->-1} craziness
- To: mathgroup at smc.vnet.net
- Subject: [mg106147] Re: More /.{I->-1} craziness
- From: David Bailey <dave at removedbailey.co.uk>
- Date: Sat, 2 Jan 2010 05:09:15 -0500 (EST)
- References: <hhf5s3$h4o$1@smc.vnet.net> <200912310816.DAA24818@smc.vnet.net> <hhkj5p$534$1@smc.vnet.net>
Murray Eisenberg wrote: > "One of the first things you learn...." Hmm... Where exactly in the > Documentation Center would one be expected to learn about replacement > rules -- and is that really one of the first things you learn there? > > When I ask this, I try to place myself in the position of somebody who > has NOT come to Mathematica with a long experience of previous versions > and their associated documentation. > > David Bailey wrote: >> .... One of the first >> things you learn about replacement rules is that they operate >> structurally, and the structure of -I (FullForm[-I]) is Complex[0,-1], >> which clearly does not match FullForm[I], which is Complex[0,1] - end of >> story! > Murray, I know what you mean - but AES is not exactly a Mathematica newbie! I suppose what I meant to say, was that when I gave introductory Mathematica courses, I covered the pitfalls of replacement rules on day one! It seems to me that the documentation post-6.0 leaves a lot to be desired, and with the constant tidal wave of new functionality arriving in Mathematica, this is something that becomes ever more serious. Incidentally, the main reason why I stopped giving courses and concentrated on consultancy, was that I felt that nobody - certainly not me - could really do justice to the functionality available. David Bailey http://www.dbaileyconsultancy.co.uk
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- Re: More /.{I->-1} craziness
- From: Murray Eisenberg <murray@math.umass.edu>
- Re: More /.{I->-1} craziness