(A)
return A.rho_D_inv
Return the (approx.) spectral radius of D^-1 * A.

    Parameters
    ----------
    A : sparse-matrix

    Returns
    -------
    approximate spectral radius of diag(A)^{-1} A

    Examples
    --------
    >>> from pyamg.gallery import poisson
    >>> from pyamg.relaxation.smoothing import rho_D_inv_A
    >>> from scipy.sparse import csr_matrix
    >>> import numpy as np
    >>> A = csr_matrix(np.array([[1.0,0,0],[0,2.0,0],[0,0,3.0]]))
    >>> print(f'{rho_D_inv_A(A):2.2}')
    1.0
Return the (approx.) spectral radius of D^-1 * A.
Return the ( approx . ) spectral radius of D^ - 1 * A .
def rho_D_inv_A(A):
    """Return the (approx.) spectral radius of D^-1 * A.

    Parameters
    ----------
    A : sparse-matrix

    Returns
    -------
    approximate spectral radius of diag(A)^{-1} A

    Examples
    --------
    >>> from pyamg.gallery import poisson
    >>> from pyamg.relaxation.smoothing import rho_D_inv_A
    >>> from scipy.sparse import csr_matrix
    >>> import numpy as np
    >>> A = csr_matrix(np.array([[1.0,0,0],[0,2.0,0],[0,0,3.0]]))
    >>> print(f'{rho_D_inv_A(A):2.2}')
    1.0

    """
    if not hasattr(A, 'rho_D_inv'):
        D_inv = get_diagonal(A, inv=True)
        D_inv_A = scale_rows(A, D_inv, copy=True)
        A.rho_D_inv = approximate_spectral_radius(D_inv_A)

    return A.rho_D_inv
def rho_D_inv_A ( A ) : if not hasattr ( A , 'rho_D_inv' ) : D_inv = get_diagonal ( A , inv = True ) D_inv_A = scale_rows ( A , D_inv , copy = True ) A . rho_D_inv = approximate_spectral_radius ( D_inv_A ) return A . rho_D_inv