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MathGroup Archive 2004

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Re: More on Delete Problems

  • To: mathgroup at smc.vnet.net
  • Subject: [mg51572] Re: [mg51551] More on Delete Problems
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Sat, 23 Oct 2004 00:22:01 -0400 (EDT)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <200410220221.WAA07306@smc.vnet.net>
  • Reply-to: murray at math.umass.edu
  • Sender: owner-wri-mathgroup at wolfram.com

Hi Gove,

You didn't say what version of Mathematica or which version of Windows.

With Mathematica 5.0.1 under Windows XP Pro SP2, your input gives no 
crash, but rather the expected result:

   a = {{1., 2., 3.}, {4., 5., 6.}};
   b = {{1, 0, 1}, {0, -2, 3}, {0, 1, 0}};
   c = a.b;
   Delete[c, {1, 1}]
{{-1., 7.}, {4., -4., 19.}}

Note that this list of lists does NOT represent a 2-by-2 matrix!  Were 
you by any chance trying to delete the 1st row and the 1st column of the 
result, or just, as you show, the 1st element of the 1st list of the 
two-element list of lists?

Gove Effinger wrote:
> Here's simple code which bombs for me:
> 
> a={{1.,2.,3.},{4.,5.,6.}}
> 
> b = {{1,0,1},{0,-2,3}, {0,1,0}}
> 
> c = a . b
> 
> Delete[c,{1,1}]
> 
> Why?
> 
> G. Effinger
> 
> 
> 
> 

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305


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