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MathGroup Archive 1999

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Re: Dealing with submatrices

  • To: mathgroup at
  • Subject: [mg18161] Re: [mg18099] Dealing with submatrices
  • From: Murray Eisenberg <murray at>
  • Date: Sat, 19 Jun 1999 23:54:26 -0400
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <7kcl6a$>
  • Sender: owner-wri-mathgroup at

Although the original submission did not specify how the elements of the
given nine 3-by-3 matrices were to be arranged in the resulting big
matrix, I suspect the desire was to insert them directly as "blocks".  

The Hanlon code below does not do that, but rather stretches out into a
single row of 9 elements the 3*3 = 9 elements of each of the given

BobHanlon at wrote:
> Chris,
> M1 = { {m111, m112, m113}, {m121, m122, m123}, {m131, m132, m133}};
> M2 = { {m211, m212, m213}, {m221, m222, m223}, {m231, m232, m233}};
> M3 = { {m311, m312, m313}, {m321, m322, m323}, {m331, m332, m333}};
> M4 = { {m411, m412, m413}, {m421, m422, m423}, {m431, m432, m433}};
> M5 = { {m511, m512, m513}, {m521, m522, m523}, {m531, m532, m533}};
> M6 = { {m611, m612, m613}, {m621, m622, m623}, {m631, m632, m633}};
> M7 = { {m711, m712, m713}, {m721, m722, m723}, {m731, m732, m733}};
> M8 = { {m811, m812, m813}, {m821, m822, m823}, {m831, m832, m833}};
> M9 = { {m911, m912, m913}, {m921, m922, m923}, {m931, m932, m933}};
> M = Partition[Flatten[{{M1, M2, M3}, {M4, M5, M6}, {M7, M8, M9}}], 9]
> Bob Hanlon
> In a message dated 6/17/99 6:26:39 PM, chall at writes:
> >I want to construct a 9x9 matrix using 9 existing 3x3 matrices:
> >M = { {m11, m12, m13}, {m21, m22, m23}, {m31, m32, m33}}
> >
> >The problem is that this creates a too-deep nested list and I can't
> >figure out how
> >to make it a 9x9.  Flatten doesn't appear to be the right tool.
> >

Murray Eisenberg                     murray at
Mathematics & Statistics Dept.       phone 413 549-1020 (H)
Univ. of Massachusetts                     413 545-2859 (W)
Amherst, MA 01003-4515

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