infinity expression from matrix inverse

• To: mathgroup at smc.vnet.net
• Subject: [mg49800] infinity expression from matrix inverse
• From: "Xiao Huang" <xiaohda at hotmail.com>
• Date: Sun, 1 Aug 2004 04:10:03 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```Dear Friends,

Recently I've been having this problem with Mathematica 5.0: In the follwing
program, when I set t=2 to 11, mathematica can give me the inverse of matrix
n0, but for t >=12, it fails to produce the inverse due to infinity
expressions. Can anyone explain this to me? (I guess the problem occurs in
the last line.) Thanks a lot!  Those a1,a2,n0,n0s,nn,c you see in the
following program are just some matrices.

Best Regards,

Xiao

\!\(<< LinearAlgebra`MatrixManipulation`\[IndentingNewLine]
\(Remove["\<Global`*\>"];\)\[IndentingNewLine]
\(ó = 8;\)\[IndentingNewLine]
\(t = 11;\)\[IndentingNewLine]
\(â = 0.6;\)\[IndentingNewLine]
\(a1 = AppendRows[\ \ \ \ IdentityMatrix[\ t - 1\ ]\ , \ \ \ Table[\ 0\ ,
\ \
{\ t - 1\ }, \ {\ 1\ }\ ]\ \ \ \ ];\)\[IndentingNewLine]
\(a2 = AppendRows[\ \ \ \ Table[\ 0\ , \ {\ t - 1\ }, \ {\ 1\ }\ ]\ , \ \
\
IdentityMatrix[\ t - 1\ ]\ \ \ \ \ ];\)\[IndentingNewLine]
\(nn = Transpose[a1] . a1;\)\[IndentingNewLine]
\(n1 = Transpose[a1] . a2;\)\[IndentingNewLine]
\(c = IdentityMatrix[t] + AppendColumns[\ Table[0, \ {1}, \ {t}],
AppendRows[\ \ \(-â\)*IdentityMatrix[t - 1], \
Table[\ 0, \ {t - 1}, \ {1}\ ]\ ]\ ];\)\[IndentingNewLine]
\(vc = ó\^2*Inverse[c] . Transpose[Inverse[c]];\)\[IndentingNewLine]
\(n0 = IdentityMatrix[t]\  + \ 2  x*vc . nn;\)\[IndentingNewLine]
\(Print[\ MatrixForm[n0]\ ];\)\[IndentingNewLine]
\(n2 = Inverse[n0] . vc;\)\[IndentingNewLine]
\)

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```

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