Re: Undiscovered Bug?

*To*: mathgroup at smc.vnet.net*Subject*: [mg46885] Re: Undiscovered Bug?*From*: lalu_bhatt at yahoo.com (Bhuvanesh)*Date*: Fri, 12 Mar 2004 23:39:44 -0500 (EST)*References*: <c2rnrf$p4h$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Harold.Noffke at wpafb.af.mil (Harold Noffke) wrote: > MathGroup: > > In Mathematica 5.0.1 with Windows 2000, I mistakenly used the [[{}]] > operator on x/y. I was expecting an error, but I kept getting unusual > results as shown in In/Out's 2 to 5 below. > > Have I stumbled on a bug, or is there a way to make sense out of this? This is the expected behavior. Quoting from the RefGuide entry for Part: expr[[ {i1, i2, ?} ]] gives a list of the parts i1, i2, ? of expr. When expr is a list, expr[[ {i1, i2, ?} ]] gives a list of parts. In general, the head of expr is applied to the list of parts. Example: In[1]:= expr = a[b,c]; In[2]:= expr[[{0,1,2}]] Out[2]= a[a, b, c] In[3]:= Apply[Head[expr], Map[Part[expr,#]&, {0,1,2}]] Out[3]= a[a, b, c] Cheers, Bhuvanesh, Wolfram Research. -- Disclaimer: Any opinions expressed herein are my own and not necessarily those of Wolfram Research.