From: israel@math.ubc.ca (Robert Israel) Subject: Re: Real Matrix log Date: 8 Feb 2001 23:58:23 GMT Newsgroups: sci.math Summary: Which matrices have 'logarithms' ? In article <95v5a8$gq9$1@nnrp1.deja.com>, wrote: >Which n by n real matrices A can be written as A= e^(B) where B is also >n by n real matrix ? The requirements are, I think: 1) A is nonsingular 2) For each negative eigenvalue -r, the dimensions of the spaces {x: (A + rI)^k x = 0} are all even. Robert Israel israel@math.ubc.ca Department of Mathematics http://www.math.ubc.ca/~israel University of British Columbia Vancouver, BC, Canada V6T 1Z2