petsc-master 2018-01-18
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computes the gradient using finite differences.


#include "petsctao.h"  
PetscErrorCode TaoDefaultComputeGradient(Tao tao,Vec Xin,Vec G,void *dummy)
Collective on Tao

Input Parameters

tao - the Tao context
X - compute gradient at this point
dummy - not used

Output Parameters

G -Gradient Vector

Options Database Key

-tao_fd_gradient - activates TaoDefaultComputeGradient()
-tao_fd_delta <delta> - change in X used to calculate finite differences


This routine is slow and expensive, and is not currently optimized to take advantage of sparsity in the problem. Although TaoDefaultComputeGradient is not recommended for general use in large-scale applications, It can be useful in checking the correctness of a user-provided gradient. Use the tao method TAOTEST to get an indication of whether your gradient is correct. This finite difference gradient evaluation can be set using the routine TaoSetGradientRoutine() or by using the command line option -tao_fd_gradient

See Also


Index of all Tao routines
Table of Contents for all manual pages
Index of all manual pages