Matlab-condition number of a matrix

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evi 2013-11-23

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评论： evi 2013-11-24

Using matlab,I found that the condition number of matrix A(using the infinity norm,Koo(A)) (where A is is the Hilbert matrix with dimension n=200 ) is 3.8586e+020

Is this right or am I wrong?

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John D'Errico 2013-11-23

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No. It is probably a bigger number than that However, you forget the limits of floating point arithmetic.

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evi 2013-11-24

Nice...Thank you...!

John D'Errico 2013-11-24

As a followup, I decided to add a few linear algebra tools to HPF. So far this am, chol, LU, det were easy and now done. svd will take longer.

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evi 2013-11-24

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I have also an other question.If we have the tridiagonal matrix,that has the number 4 at the main diagonal and the number 1 at the first diagonal below the main diagonal and at the first diagonal above the main diagonal,I get that the condition number,using the infinity norm,is 3,independent from the dimension I give..Is this right???If yes,why does this happen??Why isn't there any change of the condition number??

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John D'Errico 2013-11-24

编辑：John D'Errico 2013-11-24

If you want to ask a separate question, then ask it as another question, not as an answer to your first question. When you ask it like this, you cause confusion, and make it difficult for others to follow.

evi 2013-11-24