Diagonal extraction from QT matrices

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Given a QT matrix $A$ with finite or infinite size, the command diag extracts another QT matrix that only contains diagonal entries. Thanks to the Toeplitz structure, this vector will be almost constant, with the only exception of the top and bottom entries due to the compact correction.

Contents

Syntax

Example

We build a $6 \times 6$ QT matrix with corrections only in the entries in position $(1,1)$ and $(6,6)$, extract the diagonal part and convert it to a full matrix using the full command.

A = cqt([1 2], [1 2], -1, -2, 6, 6);
d = full(diag(A))

d =

     0     0     0     0     0     0
     0     1     0     0     0     0
     0     0     1     0     0     0
     0     0     0     1     0     0
     0     0     0     0     1     0
     0     0     0     0     0    -1