bertini::tracking::TrackerConfig Struct Reference

The thresholds a tracker judges a path against: close enough, and too big. More...

#include <config.hpp>

Public Attributes
Predictor	predictor = Predictor::RKF45
	The ODE method used to predict the next point along the path. RKF45 – order 4 with an embedded error estimate – is the default; a lower-order choice is how a path crossing is usually provoked.
NumErrorT	tracking_tolerance = NumErrorT(1e-5)
	How tightly Newton must correct onto the path for a step to be accepted.
NumErrorT	path_truncation_threshold = NumErrorT(1e5)
	The tracker abandons a path once the largest coordinate of its dehomogenized point exceeds this. Bertini 1's PathTruncationThreshold; B1 default 1e5.

Detailed Description

The thresholds a tracker judges a path against: close enough, and too big.

The tracker's own, because the tracker is what acts on them – it accepts a step or abandons a path mid-flight, and no later stage can undo either. Held in a config, like everything else a tracker is configured by, so they are set and read the one way and appear in the configuration reference (b2#457).

path_truncation_threshold is distinct from the two later questions of the same shape, deliberately, as in Bertini 1: the endgame's Security::max_norm bails out during the endgame, and the solver's endpoint_finite_threshold classifies a finished endpoint.

A solver drives tracking_tolerance per phase – loose to the endgame boundary, tight through the endgame – so expect it to change under you mid-solve. That is the algorithm doing its job, not a setting being ignored.

Member Data Documentation

path_truncation_threshold

NumErrorT bertini::tracking::TrackerConfig::path_truncation_threshold = NumErrorT(1e5)

The tracker abandons a path once the largest coordinate of its dehomogenized point exceeds this. Bertini 1's PathTruncationThreshold; B1 default 1e5.

predictor

Predictor bertini::tracking::TrackerConfig::predictor = Predictor::RKF45

The ODE method used to predict the next point along the path. RKF45 – order 4 with an embedded error estimate – is the default; a lower-order choice is how a path crossing is usually provoked.

tracking_tolerance

NumErrorT bertini::tracking::TrackerConfig::tracking_tolerance = NumErrorT(1e-5)

How tightly Newton must correct onto the path for a step to be accepted.