int SNESDefaultMatrixFreeMatCreate(SNES snes,Vec x, Mat *J)Collective on SNES and Vec
| snes | - the SNES context |
| x | - vector where SNES solution is to be stored. |
J(u)*a = [J(u+h*a) - J(u)]/h where
h = error_rel*u'a/||a||^2 if |u'a| > umin*||a||_{1}
= error_rel*umin*sign(u'a)*||a||_{1}/||a||^2 otherwise
where
error_rel = square root of relative error in function evaluation
umin = minimum iterate parameter
The user can set these parameters via SNESSetMatrixFreeParameters(). See the nonlinear solvers chapter of the users manual for details.
The user should call MatDestroy() when finished with the matrix- freematrix context.
| -snes_mf_err <error_rel> | - Sets error_rel |
| -snes_mf_unim <umin> | - Sets umin |
Location: src/snes/interface/snesmfj.c
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