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Re: FixedPoint vs. FixedPointList

• To: mathgroup at smc.vnet.net
• Subject: [mg24442] Re: [mg24384] FixedPoint vs. FixedPointList
• From: Otto Linsuain <linsuain+ at andrew.cmu.edu>
• Date: Tue, 18 Jul 2000 00:58:42 -0400 (EDT)
• References: <B594CE45.759F%andrzej@tuins.ac.jp>
• Sender: owner-wri-mathgroup at wolfram.com

 Thanks to all that replied, (and to those who thought about the problem
and couldn't find a solution, I thank you too for your time).

 I have gotten two solutions to the problem of counting how many times f
is applied in 

 FixedPoint[f,x], without using FixedPointList

 One solution, proposed by Bob Hanlon and Andrzej Kozlowski, is

 
 FixedPoint[(counter++;f[#])&,x]

 where counter is initialized to zero or one.

 Another solution, proposed by Fred Simons, is

 FixedPoint[f,x, SameTest :> (counter++;yourtest&)]

 I must admit that both solutions kept me confused for a while. I
believe I understand now that the reason they work is because the
expressions before the semicolon produce no output. Thanks again. Otto
Linsuain.