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File Content: `utils.py`

from __future__ import division, print_function, absolute_import

__docformat__ = "restructuredtext en"

__all__ = []

from warnings import warn

from numpy import asanyarray, asarray, asmatrix, array, matrix, zeros

from scipy.sparse.linalg.interface import aslinearoperator, LinearOperator, \
     IdentityOperator

_coerce_rules = {('f','f'):'f', ('f','d'):'d', ('f','F'):'F',
                 ('f','D'):'D', ('d','f'):'d', ('d','d'):'d',
                 ('d','F'):'D', ('d','D'):'D', ('F','f'):'F',
                 ('F','d'):'D', ('F','F'):'F', ('F','D'):'D',
                 ('D','f'):'D', ('D','d'):'D', ('D','F'):'D',
                 ('D','D'):'D'}


def coerce(x,y):
    if x not in 'fdFD':
        x = 'd'
    if y not in 'fdFD':
        y = 'd'
    return _coerce_rules[x,y]


def id(x):
    return x


def make_system(A, M, x0, b, xtype=None):
    """Make a linear system Ax=b

    Parameters
    ----------
    A : LinearOperator
        sparse or dense matrix (or any valid input to aslinearoperator)
    M : {LinearOperator, Nones}
        preconditioner
        sparse or dense matrix (or any valid input to aslinearoperator)
    x0 : {array_like, None}
        initial guess to iterative method
    b : array_like
        right hand side
    xtype : {'f', 'd', 'F', 'D', None}, optional
        dtype of the x vector

    Returns
    -------
    (A, M, x, b, postprocess)
        A : LinearOperator
            matrix of the linear system
        M : LinearOperator
            preconditioner
        x : rank 1 ndarray
            initial guess
        b : rank 1 ndarray
            right hand side
        postprocess : function
            converts the solution vector to the appropriate
            type and dimensions (e.g. (N,1) matrix)

    """
    A_ = A
    A = aslinearoperator(A)

    if A.shape[0] != A.shape[1]:
        raise ValueError('expected square matrix, but got shape=%s' % (A.shape,))

    N = A.shape[0]

    b = asanyarray(b)

    if not (b.shape == (N,1) or b.shape == (N,)):
        raise ValueError('A and b have incompatible dimensions')

    if b.dtype.char not in 'fdFD':
        b = b.astype('d')  # upcast non-FP types to double

    def postprocess(x):
        if isinstance(b,matrix):
            x = asmatrix(x)
        return x.reshape(b.shape)

    if xtype is None:
        if hasattr(A,'dtype'):
            xtype = A.dtype.char
        else:
            xtype = A.matvec(b).dtype.char
        xtype = coerce(xtype, b.dtype.char)
    else:
        warn('Use of xtype argument is deprecated. '
                'Use LinearOperator( ... , dtype=xtype) instead.',
                DeprecationWarning)
        if xtype == 0:
            xtype = b.dtype.char
        else:
            if xtype not in 'fdFD':
                raise ValueError("xtype must be 'f', 'd', 'F', or 'D'")

    b = asarray(b,dtype=xtype)  # make b the same type as x
    b = b.ravel()

    if x0 is None:
        x = zeros(N, dtype=xtype)
    else:
        x = array(x0, dtype=xtype)
        if not (x.shape == (N,1) or x.shape == (N,)):
            raise ValueError('A and x have incompatible dimensions')
        x = x.ravel()

    # process preconditioner
    if M is None:
        if hasattr(A_,'psolve'):
            psolve = A_.psolve
        else:
            psolve = id
        if hasattr(A_,'rpsolve'):
            rpsolve = A_.rpsolve
        else:
            rpsolve = id
        if psolve is id and rpsolve is id:
            M = IdentityOperator(shape=A.shape, dtype=A.dtype)
        else:
            M = LinearOperator(A.shape, matvec=psolve, rmatvec=rpsolve,
                               dtype=A.dtype)
    else:
        M = aslinearoperator(M)
        if A.shape != M.shape:
            raise ValueError('matrix and preconditioner have different shapes')

    return A, M, x, b, postprocess
Name	Size	Permission
__pycache__	---	0755
tests	---	0755
__init__.py	396 bytes	0644
_iterative.cpython-35m-x86_64-linux-gnu.so	251904 bytes	0755
iterative.py	21221 bytes	0644
lgmres.py	11239 bytes	0644
lsmr.py	13048 bytes	0644
lsqr.py	17950 bytes	0644
minres.py	9207 bytes	0644
setup.py	1408 bytes	0644
utils.py	3840 bytes	0644
File Content: utils.py

File Content: `utils.py`
