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SpECTRE
v2024.04.12
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Sufficient decrease parameter of the line search globalization. More...
#include <Tags.hpp>
Public Types | |
| using | type = double |
| using | group = OptionsGroup |
Static Public Member Functions | |
| static type | lower_bound () |
| static type | upper_bound () |
| static type | suggested_value () |
Static Public Attributes | |
| static constexpr Options::String | help |
Sufficient decrease parameter of the line search globalization.
The sufficient decrease parameter is the acceptable decrease of the residual magnitude in each step of the nonlinear solver. It is measured as a fraction of the predicted decrease in residual magnitude if the problem was linear. For example, a sufficient decrease parameter of 1 means that a nonlinear solver step is expected to decrease the residual exactly as expected for a linear problem, i.e. immediately to zero. A sufficient decrease parameter of 0.5 means that decreasing the residual by half of that amount in each nonlinear solver step is acceptable.
Nonlinear solver steps that fail the sufficient decrease condition (also known as Armijo condition) undergo a globalization procedure such as a line search.
A typical value for the sufficient decrease parameter is \(10^{-4}\). Set to values closer to unity when the nonlinear solver overshoots, e.g. when the initial guess is particularly bad. Larger values mean the nonlinear solver is stricter with accepting steps, preferring to apply the globalization strategy.
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staticconstexpr |