petscmaster 20150131
SNESObjectiveComputeFunctionDefaultFD
Computes the gradient of a user provided objective
Synopsis
PetscErrorCode SNESObjectiveComputeFunctionDefaultFD(SNES snes,Vec X,Vec F,void *ctx)
Collective on SNES
Input Parameter
 snes   the SNES context

 X   the state vector

 ctx   the (ignored) function context

Output Parameter
F the function value
Options Database Key
 snes_fd_function_eps   The differencing parameter

 snes_fd_function   Compute function from user provided objective with finite difference

Notes
SNESObjectiveComputeFunctionDefaultFD is similar in character to SNESComputeJacobianDefault.
Therefore, it should be used for debugging purposes only. Using it in conjunction with
SNESComputeJacobianDefault is excessively costly and produces a Jacobian that is quite
noisy. This is often necessary, but should be done with a grain of salt, even when debugging
small problems.
Note that this uses quadratic interpolation of the objective to form each value in the function.
Keywords
SNES, objective, debugging, finite differences, function
See Also
SNESSetFunction(), SNESComputeObjective(), SNESComputeJacobianDefault()
Level:advanced
Location:src/snes/interface/snesob.c
Index of all SNES routines
Table of Contents for all manual pages
Index of all manual pages