petsc-3.8.4 2018-03-24

SNESLINESEARCHBT

Backtracking line search. This line search finds the minimum of a polynomial fitting of the L2 norm of the function or the objective function if it is provided with SNESSetObjective(). If this fit does not satisfy the conditions for progress, the interval shrinks and the fit is reattempted at most max_it times or until lambda is below minlambda.

Options Database Keys

	-snes_linesearch_alpha<1e	- 4> - slope descent parameter
	-snes_linesearch_damping<1.0>	- initial step length
	-snes_linesearch_maxstep <length>	- if the length the initial step is larger than this then the step is scaled back to be of this length at the beginning of the line search
	-snes_linesearch_max_it<40>	- maximum number of shrinking step
	-snes_linesearch_minlambda<1e	- 12> - minimum step length allowed
	-snes_linesearch_order<cubic,quadratic>	- order of the approximation

Notes

This line search is taken from "Numerical Methods for Unconstrained Optimization and Nonlinear Equations" by Dennis and Schnabel, page 325.

Keywords

SNES, SNESLineSearch, damping

SNESLINESEARCHBT

Options Database Keys

Notes

Keywords

See Also