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Re: Optimizing fixed point iteration

  • To: mathgroup at smc.vnet.net
  • Subject: [mg83133] Re: Optimizing fixed point iteration
  • From: Yaroslav Bulatov <yaroslavvb at gmail.com>
  • Date: Mon, 12 Nov 2007 05:16:42 -0500 (EST)
  • References: <fh1ckb$csj$1@smc.vnet.net><fh6cir$4b1$1@smc.vnet.net>

it should be "depth......=.....20;"

"depth equals twenty semicolon" got changed to "depth;" both times I
posted

It seems someone else had problems with code getting mangled when
posting here
http://groups.google.com/group/comp.soft-sys.math.mathematica/msg/c53ddc0eee374f7e?dmode=source


On Nov 10, 11:56 pm, David Bailey <dave at Remove_Thisdbailey.co.uk>
wrote:
> Yaroslav Bulatov wrote:
> > Can anyone see the trick to speed up the following code significantly?
>
> > depth;step=.02;
> > Table[(c = 0;
> >    NestWhile[-4 (# - a) (# - b) &, .51, (c++; Abs[#1 - #2] > .1) &, 2,
> >      depth]; c), {a, -1., 0., step}, {b, 0., 1., step}] // ArrayPlot
>
> > This makes a plot of the number of iterations needed for the quadratic
> > fixed point iterations to converge, as a function of quadratic
> > parameters, however it's too slow to get sufficient granularity
>
> Are you perhaps under the misconception that your first line has set
> your 'depth' variable?
>
> David Baileyhttp://www.dbaileyconsultancy.co.uk




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