Math geeks: How do i do eigenvalue decomposition of a scalar matrix?
I know how to find eigenvalues of a normal full-rank matrix, but how do i find the eigenvalues if the matrix is already scalar to begin with? I know i want to do det(A-I*lambda)=0, but this only gives me one of the eigenvalues, how do i find the second one?
For example how to calculate eigs(A), where A=[0.7 0; 0 0.7].
I know lambda_1 is = 0.7, and that lambda_2 is supposed to be = 1, but i dont understand why. Are the repeated eigenvalues of a scalar matrix always 1? Are the eigenvalues of B=[0.7 0 0; 0 0.7 0; 0 0 0.7] = [0.7;1;1] and if so why?
This question is in the General Section. Responses must be helpful and on-topic.