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Computes the singular value decompositions of one or more matrices.
tf.linalg.svd(
tensor, full_matrices=False, compute_uv=True, name=None
)
Computes the SVD of each inner matrix in tensor
such that
tensor[..., :, :] = u[..., :, :] * diag(s[..., :, :]) *
transpose(conj(v[..., :, :]))
# a is a tensor.
# s is a tensor of singular values.
# u is a tensor of left singular vectors.
# v is a tensor of right singular vectors.
s, u, v = svd(a)
s = svd(a, compute_uv=False)
tensor
: Tensor
of shape [..., M, N]
. Let P
be the minimum of M
and
N
.full_matrices
: If true, compute full-sized u
and v
. If false
(the default), compute only the leading P
singular vectors.
Ignored if compute_uv
is False
.compute_uv
: If True
then left and right singular vectors will be
computed and returned in u
and v
, respectively. Otherwise, only the
singular values will be computed, which can be significantly faster.name
: string, optional name of the operation.s
: Singular values. Shape is [..., P]
. The values are sorted in reverse
order of magnitude, so s[..., 0] is the largest value, s[..., 1] is the
second largest, etc.u
: Left singular vectors. If full_matrices
is False
(default) then
shape is [..., M, P]
; if full_matrices
is True
then shape is
[..., M, M]
. Not returned if compute_uv
is False
.v
: Right singular vectors. If full_matrices
is False
(default) then
shape is [..., N, P]
. If full_matrices
is True
then shape is
[..., N, N]
. Not returned if compute_uv
is False
.Mostly equivalent to numpy.linalg.svd, except that
* The order of output arguments here is s
, u
, v
when compute_uv
is
True
, as opposed to u
, s
, v
for numpy.linalg.svd.
* full_matrices is False
by default as opposed to True
for
numpy.linalg.svd.
* tf.linalg.svd uses the standard definition of the SVD
\(A = U \Sigma VH\), such that the left singular vectors of a
are
the columns of u
, while the right singular vectors of a
are the
columns of v
. On the other hand, numpy.linalg.svd returns the adjoint
\(VH\) as the third output argument.
```python
import tensorflow as tf
import numpy as np
s, u, v = tf.linalg.svd(a)
tf_a_approx = tf.matmul(u, tf.matmul(tf.linalg.diag(s), v, adjoint_b=True))
u, s, v_adj = np.linalg.svd(a, full_matrices=False)
np_a_approx = np.dot(u, np.dot(np.diag(s), v_adj))