Re: Complicated Rotation

• To: mathgroup at smc.vnet.net
• Subject: [mg27257] Re: [mg27237] Complicated Rotation
• From: Matthias Hertel <wir95cgu at studserv.uni-leipzig.de>
• Date: Wed, 14 Feb 2001 03:41:25 -0500 (EST)
• References: <200102130835.DAA06532@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Yas <yast at optushome.com.au> writes:
> So at t = 0, sf = s0.
>
> And at successive increments of time
>
> sf[1] = r[1]*s0
> sf[2] = r[2]*sf[1]
> sf[3] = r[3]*sf[2]
> |
> |
> sf[n] = r[n]*sf[n-1]
>
> Unfortunately I am not much of a programmer and I have had various attempts
> with Map and Do and Table constructs with various errors. Could someone
> please explain a method whereby I could get a list of sf values so that I
> can plot sf versus time.

FoldList[r[#2].#1 &, s0, Range[n]]

For n=5 this gives

{s0, r[1].s0, r[2].r[1].s0, r[3].r[2].r[1].s0, r[4].r[3].r[2].r[1].s0,
r[5].r[4].r[3].r[2].r[1].s0}

and if I understood you correctly, this is exactly what you wanted.
(If r[t_] and s0 are actually defined in you Mathematica session,
these expressions will of course be evaluated.) You can then give this
list to ListPlot and you're done.

Matthias

```

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