Why some eigen vector signs from C++ Armadillo are different from Python and R
问题 I was wondering why the sign of the elements in the eigen vectors from Armadillo is the opposite from other languages like Python (i.e. numpy) and R. For example: C++ using namespace arma; vec eigval; mat eigvec; // C++11 initialization mat A = { 1, -1, 0, -1, 2, -1, 0, -1, 1}; eig_sym(eigval, eigvec, A); eigvec.print("Eigen Vectors"); Output Eigen Vectors -5.7735e-01 -7.071068e-01 0.4082483 -5.7735e-01 9.714451e-e17 -0.8164966 -5.7735e-01 7.017068e-01 0.4082483 Python import numpy as np w,v