function [z, a, b, alpha, err] = alge_simple (X, show);%ALGE_SIMPLE    Algebraic least squares ellipse fit.%       %       [z, a, b, alpha, err] = alge_simple (X, show{default 0})%       fits an ellipse by minimizing the "algebraic distance"%       in the least squares sense x'A x + b'x + c = 0%       weighting the i-th data by W(i).%       Constraint: A11 + A22 == 1.%%       X: given points Pi = [X(i,1), X(i,2)]%       show: if (show == 1) make test output%%       z, a, b, alpha: parameters for found ellipse%       err: error indication%       if (err == 1), not an ellipse%       if (err == 0), ok  if (nargin < 2), show = 0; end;  b = -X(:,1).^2;  A = [X(:,1).*X(:,2), X(:,2).^2-X(:,1).^2 ...       X(:,1) X(:,2) ones(size(X(:,1)))];  x = A\b;  u = [1-x(2);x];  [z, a, b, alpha, err] = ellipse_params (u, show);end % alge_simple