`scipy.sparse.linalg._onenormest:_onenormest_core`

Signature

def _onenormest_core ( A , AT , t , itmax )

Compute a lower bound of the 1-norm of a sparse array.

A : ndarray or other linear operator: A linear operator that can produce matrix products.
AT : ndarray or other linear operator: The transpose of A.
t : int, optional: A positive parameter controlling the tradeoff between accuracy versus time and memory usage.
itmax : int, optional: Use at most this many iterations.

est : float: An underestimate of the 1-norm of the sparse array.
v : ndarray, optional: The vector such that ||Av||_1 == est*||v||_1. It can be thought of as an input to the linear operator that gives an output with particularly large norm.
w : ndarray, optional: The vector Av which has relatively large 1-norm. It can be thought of as an output of the linear operator that is relatively large in norm compared to the input.
nmults : int, optional: The number of matrix products that were computed.
nresamples : int, optional: The number of times a parallel column was observed, necessitating a re-randomization of the column.

This is algorithm 2.4.