[Numpy] Add NumPy support for np.linalg.det and np.linalg.slogdet

python/mxnet/ndarray/numpy/linalg.py

@@ -21,7 +21,7 @@
 from . import _op as _mx_nd_np
 from . import _internal as _npi
 
-__all__ = ['norm', 'svd', 'cholesky', 'inv']
+__all__ = ['norm', 'svd', 'cholesky', 'inv', 'det', 'slogdet']
 
 
 def norm(x, ord=None, axis=None, keepdims=False):
@@ -242,3 +242,113 @@ def inv(a):
             [ 0.75000006, -0.25000003]]])
     """
     return _npi.inv(a)
+
+
+def det(a):
+    r"""
+    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.])
+    """
+    return _npi.det(a)
+
+
+def slogdet(a):
+    r"""
+    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.
+    logdet : (...) array_like
+        The natural log of the absolute value of the determinant.
+    If the determinant is zero, then `sign` will be 0 and `logdet` will be
+    -Inf. In all cases, the determinant is equal to ``sign * np.exp(logdet)``.
+
+    See Also
+    --------
+    det
+
+    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]])
+    >>> (sign, logdet) = np.linalg.slogdet(a)
+    >>> (sign, logdet)
+    (-1., 0.69314718055994529)
+
+    >>> sign * np.exp(logdet)
+    -2.0
+
+    Computing log-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)
+
+    >>> sign, logdet = np.linalg.slogdet(a)
+    >>> (sign, logdet)
+    (array([-1., -1., -1.]), array([ 0.69314718,  1.09861229,  2.07944154]))
+
+    >>> sign * np.exp(logdet)
+    array([-2., -3., -8.])
+
+    This routine succeeds where ordinary `det` does not:
+    >>> np.linalg.det(np.eye(500) * 0.1)
+    0.0
+    >>> np.linalg.slogdet(np.eye(500) * 0.1)
+    (1., -1151.2925464970228)
+    """
+    return _npi.slogdet(a)

python/mxnet/numpy/linalg.py

@@ -20,7 +20,7 @@
 from __future__ import absolute_import
 from ..ndarray import numpy as _mx_nd_np
 
-__all__ = ['norm', 'svd', 'cholesky', 'inv']
+__all__ = ['norm', 'svd', 'cholesky', 'inv', 'det', 'slogdet']
 
 
 def norm(x, ord=None, axis=None, keepdims=False):
@@ -260,3 +260,113 @@ def inv(a):
             [ 0.75000006, -0.25000003]]])
     """
     return _mx_nd_np.linalg.inv(a)
+
+
+def det(a):
+    r"""
+    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.])
+    """
+    return _mx_nd_np.linalg.det(a)
+
+
+def slogdet(a):
+    r"""
+    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.
+    logdet : (...) array_like
+        The natural log of the absolute value of the determinant.
+    If the determinant is zero, then `sign` will be 0 and `logdet` will be
+    -Inf. In all cases, the determinant is equal to ``sign * np.exp(logdet)``.
+
+    See Also
+    --------
+    det
+
+    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]])
+    >>> (sign, logdet) = np.linalg.slogdet(a)
+    >>> (sign, logdet)
+    (-1., 0.69314718055994529)
+
+    >>> sign * np.exp(logdet)
+    -2.0
+
+    Computing log-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)
+
+    >>> sign, logdet = np.linalg.slogdet(a)
+    >>> (sign, logdet)
+    (array([-1., -1., -1.]), array([ 0.69314718,  1.09861229,  2.07944154]))
+
+    >>> sign * np.exp(logdet)
+    array([-2., -3., -8.])
+
+    This routine succeeds where ordinary `det` does not:
+    >>> np.linalg.det(np.eye(500) * 0.1)
+    0.0
+    >>> np.linalg.slogdet(np.eye(500) * 0.1)
+    (1., -1151.2925464970228)
+    """
+    return _mx_nd_np.linalg.slogdet(a)

python/mxnet/symbol/numpy/linalg.py

@@ -22,7 +22,7 @@
 from . import _op as _mx_sym_np
 from . import _internal as _npi
 
-__all__ = ['norm', 'svd', 'cholesky', 'inv']
+__all__ = ['norm', 'svd', 'cholesky', 'inv', 'det', 'slogdet']
 
 
 def norm(x, ord=None, axis=None, keepdims=False):
@@ -229,3 +229,113 @@ def inv(a):
             [ 0.75000006, -0.25000003]]])
     """
     return _npi.inv(a)
+
+
+def det(a):
+    r"""
+    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.])
+    """
+    return _npi.det(a)
+
+
+def slogdet(a):
+    r"""
+    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.
+    logdet : (...) array_like
+        The natural log of the absolute value of the determinant.
+    If the determinant is zero, then `sign` will be 0 and `logdet` will be
+    -Inf. In all cases, the determinant is equal to ``sign * np.exp(logdet)``.
+
+    See Also
+    --------
+    det
+
+    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]])
+    >>> (sign, logdet) = np.linalg.slogdet(a)
+    >>> (sign, logdet)
+    (-1., 0.69314718055994529)
+
+    >>> sign * np.exp(logdet)
+    -2.0
+
+    Computing log-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)
+
+    >>> sign, logdet = np.linalg.slogdet(a)
+    >>> (sign, logdet)
+    (array([-1., -1., -1.]), array([ 0.69314718,  1.09861229,  2.07944154]))
+
+    >>> sign * np.exp(logdet)
+    array([-2., -3., -8.])
+
+    This routine succeeds where ordinary `det` does not:
+    >>> np.linalg.det(np.eye(500) * 0.1)
+    0.0
+    >>> np.linalg.slogdet(np.eye(500) * 0.1)
+    (1., -1151.2925464970228)
+    """
+    return _npi.slogdet(a)

src/operator/tensor/la_op.cc

@@ -945,6 +945,7 @@ NNVM_REGISTER_OP(_backward_linalg_inverse)
 
 NNVM_REGISTER_OP(_linalg_det)
 .add_alias("linalg_det")
+.add_alias("_npi_det")
 .describe(R"code(Compute the determinant of a matrix.
 Input is a tensor *A* of dimension *n >= 2*.
 
@@ -997,6 +998,7 @@ NNVM_REGISTER_OP(_backward_linalg_det)
 
 NNVM_REGISTER_OP(_linalg_slogdet)
 .add_alias("linalg_slogdet")
+.add_alias("_npi_slogdet")
 .describe(R"code(Compute the sign and log of the determinant of a matrix.
 Input is a tensor *A* of dimension *n >= 2*.