`scipy.sparse.linalg._expm_multiply:_fragment_3_1`

source: /scipy/sparse/linalg/_expm_multiply.py :503

Signature

def _fragment_3_1 ( norm_info , n0 , tol , m_max = 55 , ell = 2 )

Summary

A helper function for the _expm_multiply_* functions.

Parameters

norm_info : LazyOperatorNormInfo: Information about norms of certain linear operators of interest.
n0 : int: Number of columns in the _expm_multiply_* B matrix.
tol : float: Expected to be $2^{- 24}$ for single precision or $2^{- 53}$ for double precision.
m_max : int: A value related to a bound.
ell : int: The number of columns used in the 1-norm approximation. This is usually taken to be small, maybe between 1 and 5.

Returns

best_m : int: Related to bounds for error control.
best_s : int: Amount of scaling.

Notes

This is code fragment (3.1) in Al-Mohy and Higham (2011). The discussion of default values for m_max and ell is given between the definitions of equation (3.11) and the definition of equation (3.12).

Aliases

scipy.sparse.linalg._expm_multiply._fragment_3_1