Condition number

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The cond command computes the condition number $\| A \| \cdot \| A^{-1} \|$ of a QT matrix.

The default is to compute the condition number with respect to the spectral norm for finite matrices, and with respect to the QT norm for infinite ones.

Another choice of norm can be given using the syntax cond(A, nrm_type), where nrm_type is some norm supported by the norm command.

Contents

Syntax

Example

The Toeplitz matrix with symbol $a(z) = z^{-1} + 3 + z$ is always well conditioned, since $a(z)$ is far from zero on the unit circle.

A = cqt([3 1], [3 1]);
cond(A)

ans =

   13.7082