I am looking for a reference to study logarithm of an invertible triangular matrix. What is a good algorithm? Are there any good reference which studies this topic both theoretically and from an algorithm view point? I am also looking for structure of the logarithm of an upper/lower triangular invertible matrix.



Logarithm of a matrix
You may want to take a look at [*"Functions of Matrices: Theory and Computation"*](http://books.google.com/books?id=S6gpNn1JmbgC&printsec=frontcover&dq=functions+of+matrices&hl=en&src=bmrr&ei=2ePrTfX3E8bFswa6_d3nCg&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCkQ6AEwAA#v=onepage&q&f=false) by Higham. Chapter 11 is specifically devoted to the matrix logarithm. In particular, the chapter contains a thorough comparison of four different numerical algorithms. 


