# MATRIX_ITERATE

Controls linear scaling iterative procedure on matrices: inversion, sqrti, etc. High-order Lanczos accelerates convergence provided it can estimate the eigenspectrum correctly. [Edit on GitHub]

## Keywords

- EPS_LANCZOS

- EPS_TARGET_FACTOR

- MAX_ITER_LANCZOS

- ORDER_LANCZOS

## Keyword descriptions

EPS_LANCZOS: real = 1.00000000E-003

  Usage: EPS_LANCZOS 1.0E-4

  Threshold for Lanczos eigenvalue estimation. [Edit on GitHub]

EPS_TARGET_FACTOR: real = 1.00000000E+001

  Usage: EPS_TARGET_FACTOR 100.0

  Multiplication factor that determines acceptable error in the iterative procedure. Acceptable error = EPS_TARGET_FACTOR * EPS_FILTER [Edit on GitHub]

MAX_ITER_LANCZOS: integer = 128

  Usage: MAX_ITER_LANCZOS 64

  Maximum number of Lanczos iterations. [Edit on GitHub]

ORDER_LANCZOS: integer = 3

  Usage: ORDER_LANCZOS 5

  Order of the Lanczos estimator. Use 0 to turn off. Do not use 1. [Edit on GitHub]