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annotate toolbox/sub.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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1 function S = sub(A, i, j)
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2 %SUB Principal submatrix.
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3 % SUB(A,i,j) is A(i:j,i:j).
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4 % SUB(A,i) is the leading principal submatrix of order i,
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5 % A(1:i,1:i), if i>0, and the trailing principal submatrix
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6 % of order ABS(i) if i<0.
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7
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8 if nargin == 2
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9 if i >= 0
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10 S = A(1:i, 1:i);
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11 else
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12 n = min(size(A));
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13 S = A(n+i+1:n, n+i+1:n);
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14 end
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15 else
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16 S = A(i:j, i:j);
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17 end