view minors.m @ 958:72cd29107a9a feature/poroelastic

Temporary changes in multiblock.DiffOp. Change traction operators in Elastic2dvariable to be true boundary operators. But adjoint FD conv test fails for dirichlet BC so need to debug!
author Martin Almquist <malmquist@stanford.edu>
date Wed, 05 Dec 2018 18:58:10 -0800
parents eaf557023fbe
children
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function [minor, sub] = minors(A, verbose)
    default_arg('verbose', true);
    [n, m] = size(A);

    if n ~= m
        error('A must be square');
    end

    sub = {};
    ks = {};

    ind = 1:n;
    for k = 1:n
        C = nchoosek(ind,k);
        for i = 1:size(C,1)
            ks{end + 1} = k;
            sub{end + 1} = A(C(i,:),C(i,:));
        end
    end

    for i = 1:length(sub)
        if verbose
            fprintf('%d:\n', ks{i});
            disp(sub{i})
        end

        minor(i) = det(sub{i});
    end
end


% A is positive semidefinite if all minors are non-negative
% A is negative semidefinite if all odd minors are non-positive and all even minors are non-negative