This line search implementation is not a line search at all; it simply uses the full step. Thus, this routine is intended for methods with well-scaled updates; i.e. Newton's method (SNESNEWTONLS), on well-behaved problems.
Options Database Keys
-snes_linesearch_damping <damping> search vector is scaled by this amount, default is 1.0
- - -snes_linesearch_norms <flag> whether to compute norms or not, default is true
For methods with ill-scaled updates (SNESNRICHARDSON, SNESNCG), a small
damping parameter may yield satisfactory but slow convergence despite
the simplicity of the line search.