petsc-3.5.4 2015-05-23

TaoDefaultComputeHessian

Computes the Hessian using finite differences.

Synopsis

#include "petsctao.h"  
PetscErrorCode TaoDefaultComputeHessian(Tao tao,Vec V,Mat H,Mat B,void *dummy)

Collective on Tao

Input Parameters

	tao	- the Tao context
	V	- compute Hessian at this point
	dummy	- not used

Output Parameters

	H	- Hessian matrix (not altered in this routine)
	B	- newly computed Hessian matrix to use with preconditioner (generally the same as H)

Options Database Key

	-tao_fd	- Activates TaoDefaultComputeHessian()
	-tao_view_hessian	- view the hessian after each evaluation using PETSC_VIEWER_STDOUT_WORLD

Notes

This routine is slow and expensive, and is not currently optimized to take advantage of sparsity in the problem. Although TaoDefaultComputeHessian() is not recommended for general use in large-scale applications, It can be useful in checking the correctness of a user-provided Hessian.

Examples

src/tao/unconstrained/examples/tutorials/minsurf2.c.html