Source: pandas Version: 0.23.3+dfsg-2 Severity: important Control: tags -1 fixed-upstream patch
np.array @ Series actually calculates Series @ np.array, which is an error for nonsquare matrices and a *wrong answer* for square matrices.
Fixed upstream by https://github.com/pandas-dev/pandas/pull/21578/commits/95d66f0e17c12a1ad661ad68c4fb49eadcf4b578
a= np.array([[ 0, -1, -2, -3, -4, -5, -6, -7, -8, -9], [ 1, 0, -1, -2, -3, -4, -5, -6, -7, -8], [ 2, 1, 0, -1, -2, -3, -4, -5, -6, -7], [ 3, 2, 1, 0, -1, -2, -3, -4, -5, -6], [ 4, 3, 2, 1, 0, -1, -2, -3, -4, -5], [ 5, 4, 3, 2, 1, 0, -1, -2, -3, -4], [ 6, 5, 4, 3, 2, 1, 0, -1, -2, -3], [ 7, 6, 5, 4, 3, 2, 1, 0, -1, -2], [ 8, 7, 6, 5, 4, 3, 2, 1, 0, -1], [ 9, 8, 7, 6, 5, 4, 3, 2, 1, 0]]) b=pd.Series(np.arange(10)) a@b array([ 285, 240, 195, 150, 105, 60, 15, -30, -75, -120]) pd.DataFrame(a)@b 0 -285 1 -240 2 -195 3 -150 4 -105 5 -60 6 -15 7 30 8 75 9 120 dtype: int64