Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2002
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2002

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Iterative application of FindRoot with adjusted started values

  • To: mathgroup at smc.vnet.net
  • Subject: [mg33026] Re: Iterative application of FindRoot with adjusted started values
  • From: KIMIC Weijnitz Peter <micweij at eka.ericsson.se>
  • Date: Tue, 26 Feb 2002 04:35:15 -0500 (EST)
  • References: <a57hd0$2kb$1@smc.vnet.net> <a5cm4n$9jj$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

About aes problem, maybe this is someting?

y[k_]:=y[k]= If[ k<2, k-1, a y[k-1] + b y[k-2] ];

Table[y[k],{k,1,5}]
 gives:
{0, -b, -a b, -a^2b - b^2, -a b^2 + a(-a^2 b - b^2)}

Is this the expected result?

I have never used this kind of construction before but it is supposed to
be used
when you want to use old values without recalculating them.


Peter W


aes wrote:

> 
> Me too.  More generally, I'd like to be able to use earlier ("already
> calculated"?) values in a table in calculating later values in the same table,
> e.g.
> 
>    y = Table[ If[ k<2, k-1, a y[[k-1}] + b y[[k-2]] ], {k, 1, 5} ]
> 
> but this doesn't work.
> 
> [To handle things like this I resort to using a DO loop to calculate values of
> yTemp[k], then stuff these values into list y; but that's probably a naive --
> maybe even dumb? -- approach.]


  • Prev by Date: Re: Numerical Differentiation using Fourier Transform
  • Next by Date: Re: scatterplot3d_movie
  • Previous by thread: Re: Re: Iterative application of FindRoot with adjusted started values
  • Next by thread: scatterplot3d_movie