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Span Set nasty bug

• To: mathgroup at smc.vnet.net
• Subject: [mg123728] Span Set nasty bug
• From: roby <roby.nowak at gmail.com>
• Date: Fri, 16 Dec 2011 05:54:36 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

Dear group & Mathematica team

I am trying to assign a non existing element member of a 2D List.
Due to the coosen Span the element should not exist respectivly not be
assigned.
when the non existing element is queried e.g. {} should be returned

please take a look on the following assignment:

In[43]:= t = Table[0, {15}, {15}];
t[[1 ;; 0, 1 ;; 1]] = 1;
t[[1 ;; 0, 1 ;; 1]]
t[[1, 1]]

Out[45]= {}

Out[46]= 0

so far so good no element gets assigned and the query works,
after changing 15 to 16 or greater the query still works but  the
following happens element [[1,1]] gets a value assigned:

In[47]:= t = Table[0, {16}, {16}];
t[[1 ;; 0, 1 ;; 1]] = 1;
t[[1 ;; 0, 1 ;; 1]]
t[[1, 1]]

Out[49]= {}

Out[50]= 1

Is this a bug or is it a feature ?

• Follow-Ups:
  • Re: Span Set nasty bug
    • From: Oliver Ruebenkoenig <ruebenko@wolfram.com>
  • Re: Span Set nasty bug
    • From: DrMajorBob <btreat1@austin.rr.com>