       Re: Special Matrix

• To: mathgroup at smc.vnet.net
• Subject: [mg28242] Re: Special Matrix
• From: "Souvik Banerjee" <s-banerjee at nwu.edu>
• Date: Fri, 6 Apr 2001 01:52:51 -0400 (EDT)
• Organization: Northwestern University, Evanston, IL, US
• References: <9ah5nq\$ps0@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Not sure if the shortest but it works:

CreateMatrix[n_] :=
Block[{r,c,m},
Needs["LinearAlgebra`MatrixManipulation`"];
r = ZeroMatrix[1, n]; m = Table[1, {n - 2}, {n - 2}];
c = ZeroMatrix[n - 2, 1];
BlockMatrix[{{r}, {c, m, c}, {r}}]
]

The bottleneck seems to be the Table[] operations. If there is a built in
function to create a matrix with a constant element then it will speed this
up.

-Souvik

Yoram Pollack <syftech at saad.org.il> wrote in message
news:9ah5nq\$ps0 at smc.vnet.net...
> Hello
> I am trying to create a "n x n" matrix with "1" in every position exept in
> first and last row, and first and last coulumn, where "0" is needed. In
> other words: sqare matrix full of  "1" sorounded by "0".
> What will be the fastest and shortest way to do it?
>
> Thanks
> Yoram
>
>
>

```

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