Mercurial > repos > public > sbplib

annotate minors.m @ 213:15d604e4e1a1 feature/beams

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Removed the data paramter from boundary_condition prototype.
author Jonatan Werpers <jonatan@werpers.com>
date Wed, 22 Jun 2016 14:40:23 +0200
parents 0a881a3dc9a9
children eaf557023fbe
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
129
0a881a3dc9a9 Cleaned up the code for minors.
Jonatan Werpers <jonatan@werpers.com>
parents: 127
diff changeset
1 function [minor, sub] = minors(A)
0a881a3dc9a9 Cleaned up the code for minors.
Jonatan Werpers <jonatan@werpers.com>
parents: 127
diff changeset
2 [n, m] = size(A);
127
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
3
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
4 if n ~= m
129
0a881a3dc9a9 Cleaned up the code for minors.
Jonatan Werpers <jonatan@werpers.com>
parents: 127
diff changeset
5 error('A must be square');
127
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
6 end
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
7
129
0a881a3dc9a9 Cleaned up the code for minors.
Jonatan Werpers <jonatan@werpers.com>
parents: 127
diff changeset
8 sub = {};
127
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
9 ks = {};
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
10
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
11 ind = 1:n;
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
12 for k = 1:n
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
13 C = nchoosek(ind,k);
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
14 for i = 1:size(C,1)
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
15 ks{end + 1} = k;
129
0a881a3dc9a9 Cleaned up the code for minors.
Jonatan Werpers <jonatan@werpers.com>
parents: 127
diff changeset
16 sub{end + 1} = A(C(i,:),C(i,:));
127
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
17 end
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
18 end
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
19
129
0a881a3dc9a9 Cleaned up the code for minors.
Jonatan Werpers <jonatan@werpers.com>
parents: 127
diff changeset
20 for i = 1:length(sub)
127
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
21 fprintf('%d:\n', ks{i});
129
0a881a3dc9a9 Cleaned up the code for minors.
Jonatan Werpers <jonatan@werpers.com>
parents: 127
diff changeset
22 disp(sub{i})
127
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
23
129
0a881a3dc9a9 Cleaned up the code for minors.
Jonatan Werpers <jonatan@werpers.com>
parents: 127
diff changeset
24 minor(i) = det(sub{i});
127
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
25 end
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
26 end
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
27
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
28
129
0a881a3dc9a9 Cleaned up the code for minors.
Jonatan Werpers <jonatan@werpers.com>
parents: 127
diff changeset
29 % A is positive semidefinite if all minors are non-negative
0a881a3dc9a9 Cleaned up the code for minors.
Jonatan Werpers <jonatan@werpers.com>
parents: 127
diff changeset
30 % A is negative semidefinite if all odd minors are non-positive and all even minors are non-negative
127
967152d7d58b Added function for printing the minors of a matrix.
Jonatan Werpers <jonatan@werpers.com>
parents:
diff changeset
31