configutils

This Cython module implements global configuration data for numerical tool, which must be available at Cython speed during simulations.

All configuration data is available via attribute config of module pub.

Many numerical integration algorithms provide error estimates. An integration result is only accepted, if the associated error estimate is lower than a given threshold value.

The default value is:

>>> from hydpy.cythons.configutils import Config
>>> config = Config()
>>> from hydpy import round_
>>> round_(config.abs_error_max)
0.01

You can pass larger value, but note that too large tolerances as the following would possible lead to poor simulation results:

>>> config.abs_error_max = 1e3
>>> round_(config.abs_error_max)
1000.0

Tolerances lower than zero or equal zero cannot be met and are thus forbidden:

>>> config.abs_error_max = 0.
Traceback (most recent call last):
...
ValueError: The numerical tolerance value `abs_error_max` must be larger than zero, but the value `0.0` was given.

Under some circumstances, numerical integration algorithms might not be able to achieve sufficient accuracy with reasonable effort. To prevent model simulations from becoming too long, one can restrict the smallest time step, with which an outer time step is allowed to be solved…

The default value is:

>>> round_(config.rel_dt_min)
0.001

You can pass larger value, but note that too large step sizes as the following would possible result in poor simulation results:

>>> config.rel_dt_min = 1.
>>> round_(config.rel_dt_min)
1.0

On the other hand, too small step sizes might result in too long simulation times:

>>> config.rel_dt_min = 0.
>>> round_(config.rel_dt_min)
0.0

Tolerances lower than zero or larger than one do not make sense and are thus forbidden:

>>> config.rel_dt_min = 1.1
Traceback (most recent call last):
...
ValueError: The smallest integration time step `_rel_dt_min` must not be smaller than zero or larger than one, but the value `1.1` was given.