sympy/sympy — pull request #8721 by zingale (2015-01-01 00:43:21+00:00)
Title: add a left_eigenvectors() method

add a left_eigenvectors() method that is a wrapper around eigenvectors().
It finds the left eigenvectors of a matrix (l A = lambda l) by taking the transpose of the system,
finding the eigenvectors of A^T, and transposing back.