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comparison toolbox/hanowa.m @ 2:c124219d7bfa draft

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Re-add the 1995 toolbox after noticing the statement in the ~higham/mctoolbox/ webpage.
author Antonio Pino Robles <data.script93@gmail.com>
date Thu, 07 May 2015 18:36:24 +0200
parents 8f23314345f4
children
comparison
equal deleted inserted replaced
1:e471a92d17be 2:c124219d7bfa
1 function A = hanowa(n, d)
2 %HANOWA A matrix whose eigenvalues lie on a vertical line in the complex plane.
3 % HANOWA(N, d) is the N-by-N block 2x2 matrix (thus N = 2M must be even)
4 % [d*EYE(M) -DIAG(1:M)
5 % DIAG(1:M) d*EYE(M)]
6 % It has complex eigenvalues lambda(k) = d +/- k*i (1 <= k <= M).
7 % Parameter d defaults to -1.
8
9 % Reference:
10 % E. Hairer, S.P. Norsett and G. Wanner, Solving Ordinary
11 % Differential Equations I: Nonstiff Problems, Springer-Verlag,
12 % Berlin, 1987. (pp. 86-87)
13
14 if nargin == 1, d = -1; end
15
16 m = n/2;
17 if round(m) ~= m
18 error('N must be even.')
19 end
20
21 A = [ d*eye(m) -diag(1:m)
22 diag(1:m) d*eye(m)];