       Re: Manipulate with Matrices

• To: mathgroup at smc.vnet.net
• Subject: [mg113640] Re: Manipulate with Matrices
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Fri, 5 Nov 2010 05:14:28 -0500 (EST)

```Perhaps something similar to this

matrices = {
IdentityMatrix,
ConstantArray[1, {5, 5}],
ConstantArray[a, {5, 5}]};

labels = CharacterRange["a",
FromCharacterCode[ToCharacterCode["a"] +
Length[matrices] - 1]];

Manipulate[
Row[Thread[labels == matrices], ","]],
"",
"Det[" <> nn <> "] = " <>
ToString[Det[matrices[[
Position[labels, nn][[1, 1]]]]]]}],
{nn, labels}]

Bob Hanlon

---- Jay <jaiezee at gmail.com> wrote:

=============
I would like to use Manipulate on matrices. For instance, allow the
user to choose elements of a 50 by 50 matrix, and Manipulate shows the
dynamic inverse or transpose or determinant or whatever of the so
manipulated matrix. But I do not wish to specify ranges for the 2500
elements separately, but rather using matrices as objects.

For instance, I would like the user to choose a 5 by 5 matrix, whereby
the range goes from the zero matrix to the matrix with all elements
equal to 100, with initial matrix the identity matrix:

Manipulate[
Det[nn], {{nn, IdentityMatrix}, ConstantArray[0, {5, 5}],
ConstantArray[100, {5, 5}]}]

How can this be accomplished? How do I tell Mathematica that nn is a 5
by 5 matrix to start with? I would have hoped that the
initial value shows it is a 5 by 5 matrix, but I think that does not
work quite so automatically.

In that sense, neither the following works,

Manipulate[FullSimplify[Det[Array[nn, {5, 5}]]], {nn}]

Any help much appreciated!

Jay

--

Bob Hanlon

```

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