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