www.gusucode.com > matlab 案例源码 matlab代码程序 > matlab/FindConditionofIdentityMatrixExample.m
%% Find Condition of Identity Matrix % Examine why the reciprocal condition number is a more accurate measure % of singularity than the determinant. %% % Create a 5-by-5 multiple of the identity matrix. A = eye(5)*0.01; %% % This matrix is full rank and has five equal singular values, which you % can confirm by calculating |svd(A)|. %% % Calculate the determinant of |A|. det(A) %% % Although the determinant of the matrix is close to zero, |A| is actually % very well conditioned and _not_ close to being singular. %% % Calculate the reciprocal condition number of |A|. rcond(A) %% % The matrix has a reciprocal condition number of |1| and is, therefore, % very well conditioned. Use |rcond(A)| or |cond(A)| rather than |det(A)| % to confirm singularity of a matrix.