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diff toolbox/pei.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
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolbox/pei.m	Thu May 07 18:36:24 2015 +0200
@@ -0,0 +1,14 @@
+function P = pei(n, alpha)
+%PEI    Pei matrix.
+%       PEI(N, ALPHA), where ALPHA is a scalar, is the symmetric matrix
+%       ALPHA*EYE(N) + ONES(N).
+%       If ALPHA is omitted then ALPHA = 1 is used.
+%       The matrix is singular for ALPHA = 0, -N.
+
+%       Reference:
+%       M.L. Pei, A test matrix for inversion procedures,
+%       Comm. ACM, 5 (1962), p. 508.
+
+if nargin == 1, alpha = 1; end
+
+P = alpha*eye(n) + ones(n);