Re: newbie question about inserting values
- To: mathgroup at smc.vnet.net
- Subject: [mg95526] Re: newbie question about inserting values
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Tue, 20 Jan 2009 06:58:14 -0500 (EST)
- Organization: Uni Leipzig
- References: <gl4a2o$gco$1@smc.vnet.net>
- Reply-to: kuska at informatik.uni-leipzig.de
Hi,
try
test[4] /. test[n_] /; n > 0 :> n*test[(n - 1)]
and
test[4] //. test[n_] /; n > 0 :> n*test[(n - 1)]
Regards
Jens
SaintPatrick wrote:
> Hello all,
>
> Okay, take a look at this snippet from the book "Mathematica
> Navigator."
> '*****************************
> p = x + Sin[y];
>
> Consider the following example
>
> p/. x->y/.y->a
>
> y+ Sin[a]
>
> At each part of p, the rules are applied only once. Write then the
> following:
>
> p/.x->y/.y->a
>
> a+Sin[a]
>
> First x is replaced with y, and then y is replaced with a. Mathematica
> also has the command ReplaceRepeated, which is formed by //.. It
> applies the rules until the result no longer changes:
>
> p//.{x->y,y->a}
>
> a+Sin[a]
> **********************************
>
> I'm having trouble understanding what the exact difference internally
> is between
>
> p/.x->y/.y->a
>
> and
>
> p//.{x->y,y->a}
>
> I'd appreciate some enlightenment. Thanks.
>
>
> Patrick
>