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annotate minors.m @ 774:66eb4a2bbb72 feature/grids

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Remove default scaling of the system. The scaling doens't seem to help actual solutions. One example that fails in the flexural code. With large timesteps the solutions seems to blow up. One particular example is profilePresentation on the tdb_presentation_figures branch with k = 0.0005
author Jonatan Werpers <jonatan@werpers.com>
date Wed, 18 Jul 2018 15:42:52 -0700
parents eaf557023fbe
children
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eaf557023fbe Added verbose flag to semiDefIneq and minors.
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1 function [minor, sub] = minors(A, verbose)
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2 default_arg('verbose', true);
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3 [n, m] = size(A);
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5 if n ~= m
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6 error('A must be square');
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7 end
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9 sub = {};
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10 ks = {};
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11
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12 ind = 1:n;
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13 for k = 1:n
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14 C = nchoosek(ind,k);
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15 for i = 1:size(C,1)
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16 ks{end + 1} = k;
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17 sub{end + 1} = A(C(i,:),C(i,:));
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18 end
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19 end
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21 for i = 1:length(sub)
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22 if verbose
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23 fprintf('%d:\n', ks{i});
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24 disp(sub{i})
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25 end
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27 minor(i) = det(sub{i});
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28 end
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29 end
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32 % A is positive semidefinite if all minors are non-negative
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33 % A is negative semidefinite if all odd minors are non-positive and all even minors are non-negative
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