Source code for maxframe.tensor.linalg.inv

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import numpy as np
from numpy.linalg import LinAlgError

from ... import opcodes
from ..core import TensorOrder
from ..datasource import tensor as astensor
from ..operators import TensorHasInput, TensorOperatorMixin


class TensorInv(TensorHasInput, TensorOperatorMixin):
    _op_type_ = opcodes.INV

    def __call__(self, a):
        a = astensor(a)
        return self.new_tensor([a], a.shape, order=TensorOrder.C_ORDER)




def inv(a, sparse=None):
    """
    Compute the (multiplicative) inverse of a matrix.
    Given a square matrix `a`, return the matrix `ainv` satisfying
    ``dot(a, ainv) = dot(ainv, a) = eye(a.shape[0])``.

    Parameters
    ----------
    a : (..., M, M) array_like
        Matrix to be inverted.
    sparse: bool, optional
        Return sparse value or not.

    Returns
    -------
    ainv : (..., M, M) ndarray or matrix
        (Multiplicative) inverse of the matrix `a`.

    Raises
    ------
    LinAlgError
        If `a` is not square or inversion fails.

    Examples
    --------
    >>> import maxframe.tensor as mt
    >>> a = np.array([[1., 2.], [3., 4.]])
    >>> ainv = mt.linalg.inv(a)
    >>> mt.allclose(mt.dot(a, ainv), mt.eye(2)).execute()
    True

    >>> mt.allclose(mt.dot(ainv, a), mt.eye(2)).execute()
    True

    >>> ainv.execute()
    array([[ -2. ,  1. ],
           [ 1.5, -0.5]])
    """

    # TODO: using some parallel algorithm for matrix inversion.
    a = astensor(a)
    if a.ndim != 2:
        raise LinAlgError(
            f"{a.ndim}-dimensional array given. Tensor must be two-dimensional"
        )
    if a.shape[0] != a.shape[1]:
        raise LinAlgError("Input must be square")

    tiny_inv = np.linalg.inv(np.array([[1, 2], [2, 5]], dtype=a.dtype))
    sparse = sparse if sparse is not None else a.issparse()
    op = TensorInv(dtype=tiny_inv.dtype, sparse=sparse)
    return op(a)