Exemplo n.º 1
0
  def _testSvdCorrectness(self, dtype, shape):
    np.random.seed(1)
    x_np = np.random.uniform(low=-1.0, high=1.0, size=shape).astype(dtype)
    m, n = shape[-2], shape[-1]
    _, s_np, _ = np.linalg.svd(x_np)
    with self.cached_session() as sess:
      x_tf = array_ops.placeholder(dtype)
      with self.test_scope():
        s, u, v = linalg_ops.svd(x_tf, full_matrices=True)
      s_val, u_val, v_val = sess.run([s, u, v], feed_dict={x_tf: x_np})
      u_diff = np.matmul(u_val, np.swapaxes(u_val, -1, -2)) - np.eye(m)
      v_diff = np.matmul(v_val, np.swapaxes(v_val, -1, -2)) - np.eye(n)
      # Check u_val and v_val are orthogonal matrices.
      self.assertLess(np.linalg.norm(u_diff), 1e-2)
      self.assertLess(np.linalg.norm(v_diff), 1e-2)
      # Check that the singular values are correct, i.e., close to the ones from
      # numpy.lingal.svd.
      self.assertLess(np.linalg.norm(s_val - s_np), 1e-2)
      # The tolerance is set based on our tests on numpy's svd. As our tests
      # have batch dimensions and all our operations are on float32, we set the
      # tolerance a bit larger. Numpy's svd calls LAPACK's svd, which operates
      # on double precision.
      self.assertLess(
          np.linalg.norm(self._compute_usvt(s_val, u_val, v_val) - x_np), 2e-2)

      # Check behavior with compute_uv=False.  We expect to still see 3 outputs,
      # with a sentinel scalar 0 in the last two outputs.
      with self.test_scope():
        no_uv_s, no_uv_u, no_uv_v = gen_linalg_ops.svd(
            x_tf, full_matrices=True, compute_uv=False)
      no_uv_s_val, no_uv_u_val, no_uv_v_val = sess.run(
          [no_uv_s, no_uv_u, no_uv_v], feed_dict={x_tf: x_np})
      self.assertAllClose(no_uv_s_val, s_val, atol=1e-4, rtol=1e-4)
      self.assertEqual(no_uv_u_val, 0.0)
      self.assertEqual(no_uv_v_val, 0.0)
Exemplo n.º 2
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  def _testSvdCorrectness(self, dtype, shape):
    np.random.seed(1)
    x_np = np.random.uniform(low=-1.0, high=1.0, size=shape).astype(dtype)
    m, n = shape[-2], shape[-1]
    _, s_np, _ = np.linalg.svd(x_np)
    with self.session() as sess:
      x_tf = array_ops.placeholder(dtype)
      with self.test_scope():
        s, u, v = linalg_ops.svd(x_tf, full_matrices=True)
      s_val, u_val, v_val = sess.run([s, u, v], feed_dict={x_tf: x_np})
      u_diff = np.matmul(u_val, np.swapaxes(u_val, -1, -2)) - np.eye(m)
      v_diff = np.matmul(v_val, np.swapaxes(v_val, -1, -2)) - np.eye(n)
      # Check u_val and v_val are orthogonal matrices.
      self.assertLess(np.linalg.norm(u_diff), 1e-2)
      self.assertLess(np.linalg.norm(v_diff), 1e-2)
      # Check that the singular values are correct, i.e., close to the ones from
      # numpy.lingal.svd.
      self.assertLess(np.linalg.norm(s_val - s_np), 1e-2)
      # The tolerance is set based on our tests on numpy's svd. As our tests
      # have batch dimensions and all our operations are on float32, we set the
      # tolerance a bit larger. Numpy's svd calls LAPACK's svd, which operates
      # on double precision.
      self.assertLess(
          np.linalg.norm(self._compute_usvt(s_val, u_val, v_val) - x_np), 2e-2)

      # Check behavior with compute_uv=False.  We expect to still see 3 outputs,
      # with a sentinel scalar 0 in the last two outputs.
      with self.test_scope():
        no_uv_s, no_uv_u, no_uv_v = gen_linalg_ops.svd(
            x_tf, full_matrices=True, compute_uv=False)
      no_uv_s_val, no_uv_u_val, no_uv_v_val = sess.run(
          [no_uv_s, no_uv_u, no_uv_v], feed_dict={x_tf: x_np})
      self.assertAllClose(no_uv_s_val, s_val, atol=1e-4, rtol=1e-4)
      self.assertEqual(no_uv_u_val.shape, tensor_shape.TensorShape([0]))
      self.assertEqual(no_uv_v_val.shape, tensor_shape.TensorShape([0]))
Exemplo n.º 3
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def svd(matrix, compute_uv=True, full_matrices=False, name=None):
  """Computes the singular value decomposition of a matrix.

  Computes the SVD of `matrix` such that `matrix = u * diag(s) *
  transpose(v)`

  ```prettyprint
  # a is a matrix.
  # s is a vector of singular values.
  # u is the matrix of left singular vectors.
  # v is a matrix of right singular vectors.
  s, u, v = svd(a)
  s = svd(a, compute_uv=False)
  ```

  Args:
    matrix: `Tensor` of shape `[M, N]`. Let `P` be the minimum of `M` and `N`.
    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.
    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`.
    name: string, optional name of the operation.

  Returns:
    s: Singular values. Shape is `[P]`.
    u: Right 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: Left 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`.
  """
  s, u, v = gen_linalg_ops.svd(matrix,
                               compute_uv=compute_uv,
                               full_matrices=full_matrices)
  if compute_uv:
    return s, u, v
  else:
    return s
Exemplo n.º 4
0
def svd(matrix, compute_uv=True, full_matrices=False, name=None):
    """Computes the singular value decomposition of a matrix.

  Computes the SVD of `matrix` such that `matrix = u * diag(s) *
  transpose(v)`

  ```prettyprint
  # a is a matrix.
  # s is a vector of singular values.
  # u is the matrix of left singular vectors.
  # v is a matrix of right singular vectors.
  s, u, v = svd(a)
  s = svd(a, compute_uv=False)
  ```

  Args:
    matrix: `Tensor` of shape `[M, N]`. Let `P` be the minimum of `M` and `N`.
    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.
    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`.
    name: string, optional name of the operation.

  Returns:
    s: Singular values. Shape is `[P]`.
    u: Right 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: Left 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`.
  """
    s, u, v = gen_linalg_ops.svd(matrix,
                                 compute_uv=compute_uv,
                                 full_matrices=full_matrices)
    if compute_uv:
        return s, u, v
    else:
        return s
Exemplo n.º 5
0
def norm(tensor,
         ord='euclidean',
         axis=None,
         keepdims=None,
         name=None,
         keep_dims=None):
    r"""Computes the norm of vectors, matrices, and tensors.

  This function can compute several different vector norms (the 1-norm, the
  Euclidean or 2-norm, the inf-norm, and in general the p-norm for p > 0) and
  matrix norms (Frobenius, 1-norm, 2-norm and inf-norm).

  Args:
    tensor: `Tensor` of types `float32`, `float64`, `complex64`, `complex128`
    ord: Order of the norm. Supported values are 'fro', 'euclidean',
      `1`, `2`, `np.inf` and any positive real number yielding the corresponding
      p-norm. Default is 'euclidean' which is equivalent to Frobenius norm if
      `tensor` is a matrix and equivalent to 2-norm for vectors.
      Some restrictions apply:
        a) The Frobenius norm `fro` is not defined for vectors,
        b) If axis is a 2-tuple (matrix norm), only 'euclidean', 'fro', `1`,
           `2`, `np.inf` are supported.
      See the description of `axis` on how to compute norms for a batch of
      vectors or matrices stored in a tensor.
    axis: If `axis` is `None` (the default), the input is considered a vector
      and a single vector norm is computed over the entire set of values in the
      tensor, i.e. `norm(tensor, ord=ord)` is equivalent to
      `norm(reshape(tensor, [-1]), ord=ord)`.
      If `axis` is a Python integer, the input is considered a batch of vectors,
      and `axis` determines the axis in `tensor` over which to compute vector
      norms.
      If `axis` is a 2-tuple of Python integers it is considered a batch of
      matrices and `axis` determines the axes in `tensor` over which to compute
      a matrix norm.
      Negative indices are supported. Example: If you are passing a tensor that
      can be either a matrix or a batch of matrices at runtime, pass
      `axis=[-2,-1]` instead of `axis=None` to make sure that matrix norms are
      computed.
    keepdims: If True, the axis indicated in `axis` are kept with size 1.
      Otherwise, the dimensions in `axis` are removed from the output shape.
    name: The name of the op.
    keep_dims: Deprecated alias for `keepdims`.

  Returns:
    output: A `Tensor` of the same type as tensor, containing the vector or
      matrix norms. If `keepdims` is True then the rank of output is equal to
      the rank of `tensor`. Otherwise, if `axis` is none the output is a scalar,
      if `axis` is an integer, the rank of `output` is one less than the rank
      of `tensor`, if `axis` is a 2-tuple the rank of `output` is two less
      than the rank of `tensor`.

  Raises:
    ValueError: If `ord` or `axis` is invalid.

  @compatibility(numpy)
  Mostly equivalent to numpy.linalg.norm.
  Not supported: ord <= 0, 2-norm for matrices, nuclear norm.
  Other differences:
    a) If axis is `None`, treats the flattened `tensor` as a vector
     regardless of rank.
    b) Explicitly supports 'euclidean' norm as the default, including for
     higher order tensors.
  @end_compatibility
  """
    keepdims = deprecation.deprecated_argument_lookup('keepdims', keepdims,
                                                      'keep_dims', keep_dims)
    if keepdims is None:
        keepdims = False

    is_matrix_norm = ((isinstance(axis, tuple) or isinstance(axis, list))
                      and len(axis) == 2)
    if is_matrix_norm:
        axis = tuple(axis)
        if (not isinstance(axis[0], int) or not isinstance(axis[1], int)
                or axis[0] == axis[1]):
            raise ValueError(
                "'axis' must be None, an integer, or a tuple of 2 unique integers"
            )
        supported_matrix_norms = ['euclidean', 'fro', 1, 2, np.inf]
        if ord not in supported_matrix_norms:
            raise ValueError(
                "'ord' must be a supported matrix norm in %s, got %s" %
                (supported_matrix_norms, ord))
    else:
        if not (isinstance(axis, int) or axis is None):
            raise ValueError(
                "'axis' must be None, an integer, or a tuple of 2 unique integers"
            )

        supported_vector_norms = ['euclidean', 1, 2, np.inf]
        if (not np.isreal(ord)
                or ord <= 0) and ord not in supported_vector_norms:
            raise ValueError("'ord' must be a supported vector norm, got %s" %
                             ord)
        if axis is not None:
            axis = (axis, )

    with ops.name_scope(name, 'norm', [tensor]):
        tensor = ops.convert_to_tensor(tensor)

        if ord in ['fro', 'euclidean', 2, 2.0]:
            if is_matrix_norm and ord in [2, 2.0]:
                rank = array_ops.rank(tensor)
                positive_axis = map_fn.map_fn(
                    lambda i: control_flow_ops.cond(i >= 0, lambda: i, lambda:
                                                    i + rank),
                    ops.convert_to_tensor(axis))
                axes = math_ops.range(rank)
                perm_before = array_ops.concat([
                    array_ops.setdiff1d(axes, positive_axis)[0], positive_axis
                ],
                                               axis=0)
                perm_after = map_fn.map_fn(
                    lambda i: math_ops.cast(array_ops.squeeze(
                        array_ops.where_v2(math_ops.equal(perm_before, i))),
                                            dtype=dtypes.int32), axes)
                permed = array_ops.transpose(tensor, perm=perm_before)
                matrix_2_norm = array_ops.expand_dims(math_ops.reduce_max(
                    math_ops.abs(
                        gen_linalg_ops.svd(permed, compute_uv=False)[0]),
                    axis=-1,
                    keepdims=True),
                                                      axis=-1)
                result = array_ops.transpose(matrix_2_norm, perm=perm_after)
            else:
                result = math_ops.sqrt(
                    math_ops.reduce_sum(tensor * math_ops.conj(tensor),
                                        axis,
                                        keepdims=True))
                # TODO(rmlarsen): Replace with the following, once gradients are defined
                # result = math_ops.reduce_euclidean_norm(tensor, axis, keepdims=True)
        else:
            result = math_ops.abs(tensor)
            if ord == 1:
                sum_axis = None if axis is None else axis[0]
                result = math_ops.reduce_sum(result, sum_axis, keepdims=True)
                if is_matrix_norm:
                    result = math_ops.reduce_max(result,
                                                 axis[-1],
                                                 keepdims=True)
            elif ord == np.inf:
                if is_matrix_norm:
                    result = math_ops.reduce_sum(result,
                                                 axis[1],
                                                 keepdims=True)
                max_axis = None if axis is None else axis[0]
                result = math_ops.reduce_max(result, max_axis, keepdims=True)
            else:
                # General p-norms (positive p only)
                result = math_ops.pow(
                    math_ops.reduce_sum(math_ops.pow(result, ord),
                                        axis,
                                        keepdims=True), 1.0 / ord)
        if not keepdims:
            result = array_ops.squeeze(result, axis)
        return result
Exemplo n.º 6
0
def svd(tensor, full_matrices=False, compute_uv=True, name=None):
    r"""Computes the singular value decompositions of one or more matrices.

  Computes the SVD of each inner matrix in `tensor` such that
  `tensor[..., :, :] = u[..., :, :] * diag(s[..., :, :]) *
   transpose(conj(v[..., :, :]))`

  ```python
  # 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)
  ```

  Args:
    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.

  Returns:
    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`.

  @compatibility(numpy)
  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 V^H\\), 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
      \\(V^H\\) 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))
  # tf_a_approx and np_a_approx should be numerically close.
  ```
  @end_compatibility
  """
    s, u, v = gen_linalg_ops.svd(tensor,
                                 compute_uv=compute_uv,
                                 full_matrices=full_matrices,
                                 name=name)
    if compute_uv:
        return math_ops.real(s), u, v
    else:
        return math_ops.real(s)
Exemplo n.º 7
0
def norm(tensor,
         ord='euclidean',
         axis=None,
         keepdims=None,
         name=None,
         keep_dims=None):
  r"""Computes the norm of vectors, matrices, and tensors.

  This function can compute several different vector norms (the 1-norm, the
  Euclidean or 2-norm, the inf-norm, and in general the p-norm for p > 0) and
  matrix norms (Frobenius, 1-norm, 2-norm and inf-norm).

  Args:
    tensor: `Tensor` of types `float32`, `float64`, `complex64`, `complex128`
    ord: Order of the norm. Supported values are 'fro', 'euclidean',
      `1`, `2`, `np.inf` and any positive real number yielding the corresponding
      p-norm. Default is 'euclidean' which is equivalent to Frobenius norm if
      `tensor` is a matrix and equivalent to 2-norm for vectors.
      Some restrictions apply:
        a) The Frobenius norm `fro` is not defined for vectors,
        b) If axis is a 2-tuple (matrix norm), only 'euclidean', 'fro', `1`,
           `2`, `np.inf` are supported.
      See the description of `axis` on how to compute norms for a batch of
      vectors or matrices stored in a tensor.
    axis: If `axis` is `None` (the default), the input is considered a vector
      and a single vector norm is computed over the entire set of values in the
      tensor, i.e. `norm(tensor, ord=ord)` is equivalent to
      `norm(reshape(tensor, [-1]), ord=ord)`.
      If `axis` is a Python integer, the input is considered a batch of vectors,
      and `axis` determines the axis in `tensor` over which to compute vector
      norms.
      If `axis` is a 2-tuple of Python integers it is considered a batch of
      matrices and `axis` determines the axes in `tensor` over which to compute
      a matrix norm.
      Negative indices are supported. Example: If you are passing a tensor that
      can be either a matrix or a batch of matrices at runtime, pass
      `axis=[-2,-1]` instead of `axis=None` to make sure that matrix norms are
      computed.
    keepdims: If True, the axis indicated in `axis` are kept with size 1.
      Otherwise, the dimensions in `axis` are removed from the output shape.
    name: The name of the op.
    keep_dims: Deprecated alias for `keepdims`.

  Returns:
    output: A `Tensor` of the same type as tensor, containing the vector or
      matrix norms. If `keepdims` is True then the rank of output is equal to
      the rank of `tensor`. Otherwise, if `axis` is none the output is a scalar,
      if `axis` is an integer, the rank of `output` is one less than the rank
      of `tensor`, if `axis` is a 2-tuple the rank of `output` is two less
      than the rank of `tensor`.

  Raises:
    ValueError: If `ord` or `axis` is invalid.

  @compatibility(numpy)
  Mostly equivalent to numpy.linalg.norm.
  Not supported: ord <= 0, 2-norm for matrices, nuclear norm.
  Other differences:
    a) If axis is `None`, treats the flattened `tensor` as a vector
     regardless of rank.
    b) Explicitly supports 'euclidean' norm as the default, including for
     higher order tensors.
  @end_compatibility
  """
  keepdims = deprecation.deprecated_argument_lookup('keepdims', keepdims,
                                                    'keep_dims', keep_dims)
  if keepdims is None:
    keepdims = False

  is_matrix_norm = ((isinstance(axis, tuple) or isinstance(axis, list)) and
                    len(axis) == 2)
  if is_matrix_norm:
    axis = tuple(axis)
    if (not isinstance(axis[0], int) or not isinstance(axis[1], int) or
        axis[0] == axis[1]):
      raise ValueError(
          "'axis' must be None, an integer, or a tuple of 2 unique integers")
    supported_matrix_norms = ['euclidean', 'fro', 1, 2, np.inf]
    if ord not in supported_matrix_norms:
      raise ValueError("'ord' must be a supported matrix norm in %s, got %s" %
                       (supported_matrix_norms, ord))
  else:
    if not (isinstance(axis, int) or axis is None):
      raise ValueError(
          "'axis' must be None, an integer, or a tuple of 2 unique integers")

    supported_vector_norms = ['euclidean', 1, 2, np.inf]
    if (not np.isreal(ord) or ord <= 0) and ord not in supported_vector_norms:
      raise ValueError("'ord' must be a supported vector norm, got %s" % ord)
    if axis is not None:
      axis = (axis,)

  with ops.name_scope(name, 'norm', [tensor]):
    tensor = ops.convert_to_tensor(tensor)

    if ord in ['fro', 'euclidean', 2, 2.0]:
      if is_matrix_norm and ord in [2, 2.0]:
        rank = array_ops.rank(tensor)
        positive_axis = map_fn.map_fn(
            lambda i: control_flow_ops.cond(i >= 0, lambda: i, lambda: i + rank),
            ops.convert_to_tensor(axis))
        axes = math_ops.range(rank)
        perm_before = array_ops.concat(
            [array_ops.setdiff1d(axes, positive_axis)[0], positive_axis],
            axis=0)
        perm_after = map_fn.map_fn(
            lambda i: math_ops.cast(
                array_ops.squeeze(
                    array_ops.where(math_ops.equal(perm_before, i))),
                dtype=dtypes.int32), axes)
        permed = array_ops.transpose(tensor, perm=perm_before)
        matrix_2_norm = array_ops.expand_dims(
            math_ops.reduce_max(
                math_ops.abs(gen_linalg_ops.svd(permed, compute_uv=False)[0]),
                axis=-1,
                keepdims=True),
            axis=-1)
        result = array_ops.transpose(matrix_2_norm, perm=perm_after)
      else:
        result = math_ops.sqrt(
            math_ops.reduce_sum(
                tensor * math_ops.conj(tensor), axis, keepdims=True))
    else:
      result = math_ops.abs(tensor)
      if ord == 1:
        sum_axis = None if axis is None else axis[0]
        result = math_ops.reduce_sum(result, sum_axis, keepdims=True)
        if is_matrix_norm:
          result = math_ops.reduce_max(result, axis[-1], keepdims=True)
      elif ord == np.inf:
        if is_matrix_norm:
          result = math_ops.reduce_sum(result, axis[1], keepdims=True)
        max_axis = None if axis is None else axis[0]
        result = math_ops.reduce_max(result, max_axis, keepdims=True)
      else:
        # General p-norms (positive p only)
        result = math_ops.pow(
            math_ops.reduce_sum(math_ops.pow(result, ord), axis, keepdims=True),
            1.0 / ord)
    if not keepdims:
      result = array_ops.squeeze(result, axis)
    return result
Exemplo n.º 8
0
def svd(tensor, full_matrices=False, compute_uv=True, name=None):
  r"""Computes the singular value decompositions of one or more matrices.

  Computes the SVD of each inner matrix in `tensor` such that
  `tensor[..., :, :] = u[..., :, :] * diag(s[..., :, :]) *
   transpose(conj(v[..., :, :]))`

  ```python
  # 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)
  ```

  Args:
    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.

  Returns:
    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`.

  @compatibility(numpy)
  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 V^H\\), 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
      \\(V^H\\) 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))
  # tf_a_approx and np_a_approx should be numerically close.
  ```
  @end_compatibility
  """
  s, u, v = gen_linalg_ops.svd(
      tensor, compute_uv=compute_uv, full_matrices=full_matrices, name=name)
  if compute_uv:
    return math_ops.real(s), u, v
  else:
    return math_ops.real(s)