test_gage_principal_axes(
    Array[
     [1., 0., 0.],
     [0., 1., 0.],
     [1., 1., 0.]], 
    [sqrt(2)/2. -sqrt(2)/2. 0.;
     sqrt(2)/2.  sqrt(2)/2. 0.;
     0.          0.         1.], "test using array of 3 vectors as input")

