Re: ReplaceAll question
- To: mathgroup at smc.vnet.net
- Subject: [mg82540] Re: ReplaceAll question
- From: Szabolcs Horvát <szhorvat at gmail.com>
- Date: Wed, 24 Oct 2007 04:25:45 -0400 (EDT)
- References: <ffkf46$sh6$1@smc.vnet.net>
Yaroslav Bulatov wrote: > b = 3; > Hold[a[[b]]] /. {b -> c} > > ReplaceAll has no effect, why? Because 'b' gets evaluated. So this is equivalent to: Hold[a[[b]]] /. {3 -> c} > What is the recommended way of carrying > out the replacement above? > One must use HoldPattern here. b = 3; Hold[b] /. HoldPattern[b] -> c -- Szabolcs