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MathGroup Archive 2011

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Re: list equation

  • To: mathgroup at smc.vnet.net
  • Subject: [mg121973] Re: list equation
  • From: Simon <simonjtyler at gmail.com>
  • Date: Fri, 7 Oct 2011 04:50:51 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <j6jpek$me8$1@smc.vnet.net>
  • Reply-to: comp.soft-sys.math.mathematica at googlegroups.com

Using SameTest is a lot slower than sticking to the default, so you could try
lst = Tuples[Range[50], 2];
lstnew = Union[Sort /@ lst]
which is about 6000 times faster than your 
Union[lst, SameTest -> (#1 == Reverse[#2] &)]

Easier still would just be to construct
Flatten[Table[{i, j}, {i, 1, 100}, {j, i, 100}], 1]
which is about twice as fast again.



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