RE: A Recreational Endeavour

*To*: mathgroup at smc.vnet.net*Subject*: [mg8764] RE: [mg8692] A Recreational Endeavour*From*: Ersek_Ted%PAX1A at mr.nawcad.navy.mil*Date*: Sun, 21 Sep 1997 20:51:07 -0400*Sender*: owner-wri-mathgroup at wolfram.com

It looks like you have a copy of the Mathematica Book. That is very important. A very good move to make the next step is to get a copy of Power Programming with Mathematica the Kernal. by: David B. Wagner A signifigant part of this book covers "Programming for Performance". In this section he covers a lot of important lessons that many other authors do not discuss. He also covers a lot of other very good information. Ted -------------------------------------------------------------------------- |From: "haha"@astral.magic.ca at PMDF@PAXMB1 |To: ersek ted; "mathgroup"@smc.vnet.net at PMDF@PAXMB1 |Subject: [mg8764] [mg8692] A Recreational Endeavour |Date: Friday, September 19, 1997 4:25AM | |<<File Attachment: 00000000.TXT>> |I am an amateur in both Mathematica and mathematics. Consider the following |bit of (likely) very inefficient code: | |In[1]:= |x={1};y={2,3,4}; |Do[x=Append[x,y[[n+1]]]; | y=Flatten[ | Append[Transpose[ | Reverse[ReplacePart[Partition[Delete[y,n+1],n], | Reverse[First[Partition[Delete[y,n+1],n]]],1]]],{3*n+2,3*n+3, | 3*n+4}]],{n,1,100}] |x |Out[2]= |{1,3,5,4,10,7,15,8,20,9,18,24,31,14,28,22,42,35,33,46,53,6,36,23,2,55,62,59, | 76,65,54,11,34,48,70,79,99,95,44,97,58,84,25,13,122,83,26,115,82,91,52,138, | 67,90,71,119,64,37,81,39,169,88,108,141,38,16,146,41,21,175,158,165,86,191, | 45,198,216,166,124,128,204,160,12,232,126,208,114,161,156,151,249,236,263, | 243,101,121,72,120,47,229,178} | |The resulting set is a permutation of the positive Integers, with the |caveat that it is not known (and, perhaps, not knowable) if *every* number |eventually appears. | |I would like to generate x for values much greater than 100. Using |Mathematica 3.0 on a Macintosh with some 50 MB assigned to the MathKernel, |I can generate x with a Length of about 4400 before running out of memory. |If there is some way to squeeze more data points out of my existing code, I |would be pleased to hear of it. | |-- |Nature requires five, |Custom allows seven, |Idleness takes nine, |And wickedness eleven. | | | |