Re: ReplaceAll question

*To*: mathgroup at smc.vnet.net*Subject*: [mg82534] Re: ReplaceAll question*From*: Peter Pein <petsie at dordos.net>*Date*: Wed, 24 Oct 2007 04:22:41 -0400 (EDT)*References*: <ffkf46$sh6$1@smc.vnet.net>

Yaroslav Bulatov schrieb: > b = 3; > Hold[a[[b]]] /. {b -> c} > > ReplaceAll has no effect, why? What is the recommended way of carrying > out the replacement above? > > the "b" in the rule is evaluated. Use HoldPattern: In[1]:= b = 3; Hold[a[[b]]] /. {HoldPattern[b] -> c} Out[2]= Hold[a[[c]]] Peter