Multiple use of Set on lists

*To*: mathgroup at smc.vnet.net*Subject*: [mg119756] Multiple use of Set on lists*From*: Jonathan Frazer <J.Frazer at sussex.ac.uk>*Date*: Mon, 20 Jun 2011 19:38:06 -0400 (EDT)*References*: <itm0of$143$1@smc.vnet.net> <201106201204.IAA07658@smc.vnet.net>

Hello, I have a largish list of awkwardly "indexed variables", of the form cs = {c[1/2][-(1/2)][1/2][-(1/2)][-1], c[1/2][-(1/2)][1/2][1/2][-1]......etc.... ....} which need to be assigned random values multiple times inside a Do loop. I was hoping I could generate a new list of random numbers each time then do something like MapThread[Set, {cs, rands}] Where "rands" would be the list of random numbers. I'm clearly misunderstanding how MapThread works though as this doesn't work. Rather than getting "c[1/2][-(1/2)][1/2][-(1/2)][-1]=new random number", instead "old random number=new random number" is what seems to be happening. As a last resort I thought I would just clear the variables at the beginning of the do loop but you can't use Clear to do this and I don't see how you can apply "=." (Unset) over a list either. Any suggestions? Many thanks, Jonny

**References**:**Re: How to find one expression in terms of another expression?***From:*David Bailey <dave@removedbailey.co.uk>