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MathGroup Archive 2004

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Re: [Outer [Times, , ] ] Question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg45803] Re: [Outer [Times, , ] ] Question
  • From: bobhanlon at aol.com (Bob Hanlon)
  • Date: Mon, 26 Jan 2004 01:53:08 -0500 (EST)
  • References: <bv00aa$jda$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

x1 = {1, -1, -1, 1, 1};
y1 = {1, 1, -1, -1};

x2 = {-1, 1, -1, 1, -1};
y2 = {1, -1, 1, -1};

x3 = {1, 1, -1, -1, 1};
y3 = {-1, -1, 1, 1};

MatrixForm[m1=Outer [Times, x1, y1] ]
MatrixForm[m2=Outer [Times, x2, y2] ]
MatrixForm[m3=Outer [Times, x3, y3] ]

MatrixForm[mm = m1 + m2 + m3]

Or better yet, do away with all of the MatrixForm by setting your Default
Output FormatType to TraditionalForm


Bob Hanlon

In article <bv00aa$jda$1 at smc.vnet.net>, MichaelSMcCain at cs.com wrote:

<< I want to take a Column Vector and multiply it by a Row Vector to create an 
"Outer" Matrix. 

In other words, I want to take a 5x1 Column Vector and multiply it by a 1x4 
Row Vector and output a 5x4 Matrix.

I then want to add several of these Matrices together and obtain a "final" 
Matrix.

I tried the following:

x1 = {1, -1, -1, 1, 1};
y1 = {1, 1, -1, -1};

x2 = {-1, 1, -1, 1, -1};
y2 = {1, -1, 1, -1};

x3 = {1, 1, -1, -1, 1};
y3 = {-1, -1, 1, 1};

m1 = MatrixForm[Outer [Times, x1, y1] ]
m2 = MatrixForm[Outer [Times, x2, y2] ]
m3 = MatrixForm[Outer [Times, x3, y3] ]

mm = m1 + m2 + m3

MatrixForm[mm]

The output that I get is incorrect and does not combine into a single Matrix.


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