Re: Condition in replacement rule
- To: mathgroup at smc.vnet.net
- Subject: [mg67781] Re: Condition in replacement rule
- From: Bill Rowe <readnewsciv at earthlink.net>
- Date: Fri, 7 Jul 2006 07:13:07 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
On 7/6/06 at 6:52 AM, wandering.the.cosmos at gmail.com wrote: >I have a replacement rule that goes like >A[V,W_] -> A[V,W] + B[W] >but I want to perform this replacement if and only if V and W are >not the same. It seems >A[V,W_/;W!=V] -> A[V,W] + B[W] >does not seem to work. How should I do this? Using RuleDelayed the following should work A[V_,W_]:>If[W != V, A[V,W]+B[W], A[V,W]] Checking to confirm In[2]:= A[1, 2] /. A[V_, W_] :> If[W != V, A[V, W] + B[W], A[V, W]] Out[2]= A[1, 2] + B[2] In[3]:= A[1, 1] /. A[V_, W_] :> If[W != V, A[V, W] + B[W], A[V, W]] Out[3]= A[1, 1] -- To reply via email subtract one hundred and four