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Figure Properties - SERC

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gallery<br />

2-946<br />

rosser—Classic symmetric eigenvalue test matrix<br />

A = rosser returns the Rosser matrix. This matrix was a challenge for many<br />

matrix eigenvalue algorithms. But the QR algorithm, as perfected by<br />

Wilkinson and implemented in MATLAB, has no trouble with it. The matrix<br />

is 8-by-8 with integer elements. It has:<br />

A double eigenvalue<br />

Three nearly equal eigenvalues<br />

Dominant eigenvalues of opposite sign<br />

A zero eigenvalue<br />

A small, nonzero eigenvalue<br />

smoke—Complex matrix with a 'smoke ring' pseudospectrum<br />

A = gallery('smoke',n) returns an n-by-n matrix with 1’s on the<br />

superdiagonal, 1 in the (n,1) position, and powers of roots of unity along the<br />

diagonal.<br />

A = gallery('smoke',n,1) returns the same except that element A(n,1) is<br />

zero.<br />

The eigenvalues of gallery('smoke',n,1) are the nth roots of unity; those of<br />

gallery('smoke',n) are the nth roots of unity times 2^(1/n).<br />

toeppd—Symmetric positive definite Toeplitz matrix<br />

A = gallery('toeppd',n,m,w,theta) returns an n-by-n symmetric, positive<br />

semi-definite (SPD) Toeplitz matrix composed of the sum of m rank 2 (or, for<br />

certain theta, rank 1) SPD Toeplitz matrices. Specifically,<br />

T = w(1)*T(theta(1)) + ... + w(m)*T(theta(m))<br />

where T(theta(k)) has (i,j) element cos(2*pi*theta(k)*(i-j)).<br />

By default: m = n, w = rand(m,1), and theta = rand(m,1).

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