Table of Contents
Shortcuts

# torch.lu_unpack

torch.lu_unpack(LU_data, LU_pivots, unpack_data=True, unpack_pivots=True, *, out=None)

  Unpacks the LU decomposition returned by `lu_factor()` into the P, L, U matrices.

  See also

  `lu()` returns the matrices from the LU decomposition. Its gradient formula is more efficient than that of doing `lu_factor()` followed by `lu_unpack()`.

  Parameters:

    - LU_data (Tensor) – the packed LU factorization data

    - LU_pivots (Tensor) – the packed LU factorization pivots

    - unpack_data (bool) – flag indicating if the data should be unpacked. If `False`, then the returned `L` and `U` are empty tensors. Default: `True`

    - unpack_pivots (bool) – flag indicating if the pivots should be unpacked into a permutation matrix `P`. If `False`, then the returned `P` is an empty tensor. Default: `True`

  Keyword Arguments:

    out (tuple, optional) – output tuple of three tensors. Ignored if None.

  Returns:

    A namedtuple `(P, L, U)`

  Examples:

      >>> A = torch.randn(2, 3, 3)
      >>> LU, pivots = torch.linalg.lu_factor(A)
      >>> P, L, U = torch.lu_unpack(LU, pivots)
      >>> # We can recover A from the factorization
      >>> A_ = P @ L @ U
      >>> torch.allclose(A, A_)
      True

      >>> # LU factorization of a rectangular matrix:
      >>> A = torch.randn(2, 3, 2)
      >>> LU, pivots = torch.linalg.lu_factor(A)
      >>> P, L, U = torch.lu_unpack(LU, pivots)
      >>> # P, L, U are the same as returned by linalg.lu
      >>> P_, L_, U_ = torch.linalg.lu(A)
      >>> torch.allclose(P, P_) and torch.allclose(L, L_) and torch.allclose(U, U_)
      True

## Docs

Access comprehensive developer documentation for PyTorch

View Docs

## Tutorials

Get in-depth tutorials for beginners and advanced developers

View Tutorials

## Resources

Find development resources and get your questions answered

View Resources

To analyze traffic and optimize your experience, we serve cookies on this site. By clicking or navigating, you agree to allow our usage of cookies. As the current maintainers of this site, Facebook’s Cookies Policy applies. Learn more, including about available controls: Cookies Policy.