haojin2 commented on a change in pull request #15861: Numpy det and slogdet operator URL: https://github.com/apache/incubator-mxnet/pull/15861#discussion_r313719805
########## File path: python/mxnet/_numpy_op_doc.py ########## @@ -20,6 +20,129 @@ """Doc placeholder for numpy ops with prefix _np.""" +def _np_linalg_det(a): + """ + det(a) + + Compute the determinant of an array. + + Parameters + ---------- + a : (..., M, M) ndarray + Input array to compute determinants for. + + Returns + ------- + det : (...) ndarray + Determinant of `a`. + + See Also + -------- + slogdet : Another way to represent the determinant, more suitable + for large matrices where underflow/overflow may occur. + + Notes + ----- + + Broadcasting rules apply, see the `numpy.linalg` documentation for + details. + + The determinant is computed via LU factorization using the LAPACK + routine z/dgetrf. + + Examples + -------- + The determinant of a 2-D array [[a, b], [c, d]] is ad - bc: + + >>> a = np.array([[1, 2], [3, 4]]) + >>> np.linalg.det(a) + -2.0 + + Computing determinants for a stack of matrices: + + >>> a = np.array([ [[1, 2], [3, 4]], [[1, 2], [2, 1]], [[1, 3], [3, 1]] ]) + >>> a.shape + (3, 2, 2) + >>> np.linalg.det(a) + array([-2., -3., -8.]) + """ + pass + + +def _np_linalg_slogdet(a): + """ + slogdet(a) + + Compute the sign and (natural) logarithm of the determinant of an array. + + If an array has a very small or very large determinant, then a call to + `det` may overflow or underflow. This routine is more robust against such + issues, because it computes the logarithm of the determinant rather than + the determinant itself. + + Parameters + ---------- + a : (..., M, M) ndarray + Input array, has to be a square 2-D array. + + Returns + ------- + sign : (...) ndarray + A number representing the sign of the determinant. For a real matrix, + this is 1, 0, or -1. For a complex matrix, this is a complex number Review comment: we do not support complex matrices yet, please fix all docs according to our actual behaviors. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
