view minors.m @ 1031:2ef20d00b386 feature/advectionRV

For easier comparison, return both the first order and residual viscosity when evaluating the residual. Add the first order and residual viscosity to the state of the RungekuttaRV time steppers
author Vidar Stiernström <vidar.stiernstrom@it.uu.se>
date Thu, 17 Jan 2019 10:25:06 +0100
parents eaf557023fbe
children
line wrap: on
line source

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