EigenValsVecs question

Hello! I compared results of EigenValsVecs functions in IPP and OpenCV and found that in some cases ippiEigenValsVecs function returns exactly (1.0f, 0.0f) and (0.0f, 1.0f) eigen vectors although OpenCV returns eigen vectors which are not even close to vectors obtained with IPP.

For example with input 5x5 matrix

-116.127525f,      -152.685074f,       108.699646f,     -168.813187f,      166.688339f,
-195.550934f,       142.426865f,         63.002094f,       67.792168f,        66.547188f,
   40.681679f,        91.366081f,        -10.763326f,      186.464005f,      164.351349f,
   44.740143f,        64.384964f,        -80.919853f,       -29.437082f,       45.215580f,
   95.272400f,        21.906961f,         84.793060f,       -50.961384f,      250.437256f

IPP returns (1.0f, 0.0f) and (0.0f, 1.0f) eigen vectors for the (3, 3) element of the matrix, but OpenCV returns (-0.540550, 0.841312) and (-0.841312, -0.540550).

Is there any reason for such behavior or some criteria when it appear?