Re: Suggestions for translating a Do[] loop ...
- To: mathgroup at smc.vnet.net
- Subject: [mg69790] Re: Suggestions for translating a Do[] loop ...
- From: dh <dh at metrohm.ch>
- Date: Sat, 23 Sep 2006 04:44:27 -0400 (EDT)
- References: <eevtpj$hfr$1@smc.vnet.net>
Hi David;
Note that if you reverse your lists, the loop runs forward.
With list reversed:
FoldList[(#2[[1]](#2[[2]]+#1))/(1+#2[[2]] #1)&,0,Drop[Transpose[{a,b}],1]]
Daniel
David Annetts wrote:
> Hi,
>
> Given that a, b & r are lists of the same length, can anyone suggest a
> translation of the following Do[] loop to something functional? It looks
> like an ideal application for Fold, but for me, the loop going backwards is
> really obscuring things.
>
> The loop is
>
> Do[
> r[[j]] = a[[j]] * (b[[j]] + r[[j + 1]]) / (1 + b[[j]] * r[[j
> + 1]]),
> {j, Length@a - 1, 1, -1}
> ];
>
> with r[[Length@a]] = 0.
>
> Many thanks,
>
> Dave.
>