lines 8-104 of file: include/cppad/core/atomic/three/hes_sparsity.hpp

{xrst_begin atomic_three_hes_sparsity}

Atomic Function Hessian Sparsity Patterns
#########################################

Syntax
******

| *ok* = *afun* . ``hes_sparsity`` (
| |tab| *parameter_x* , *type_x* , *select_x* , *select_y* , *pattern_out*
| )

Prototype
*********
{xrst_literal
   // BEGIN_PROTOTYPE
   // END_PROTOTYPE
}

Implementation
**************
This function must be defined if
:ref:`atomic_three_ctor@atomic_user@afun` is
used to define an :ref:`ADFun-name` object *f* ,
and Hessian sparsity patterns are computed for *f* .

Base
****
See :ref:`atomic_three_afun@Base` .

parameter_x
***********
See :ref:`atomic_three_define@parameter_x` .

type_x
******
See :ref:`atomic_three_define@type_x` .

select_x
********
This argument has size equal to the number of arguments to this
atomic function; i.e. the size of *ax* .
It specifies which domain components are included in
the calculation of *pattern_out* .
If *select_x* [ *j* ] is false, then there will be no indices
*k* such that either of the following hold:

| |tab| *pattern_out* . ``row`` ()[ *k* ] == *j*
| |tab| *pattern_out* . ``col`` ()[ *k* ] == *j*

.

select_y
********
This argument has size equal to the number of results to this
atomic function; i.e. the size of *ay* .
It specifies which range component functions :math:`g_i (x)` are included in
of *pattern_out* .

pattern_out
***********
This input value of *pattern_out* does not matter.
Upon return it is the union,
with respect to *i* such that *select_y* [ *i* ] is true,
of the sparsity pattern for Hessian of :math:`g_i (x)`.
To be specific, there are non-negative indices
*i* , *r* , *c* , and *k* such that

| |tab| *pattern_out* . ``row`` ()[ *k* ] == *r*
| |tab| *pattern_out* . ``col`` ()[ *k* ] == *c*

if and only if
*select_y* [ *i* ] is true,
*select_x* [ *r* ] is true,
*select_x* [ *c* ] is true,
and

.. math::

   \partial_{x(r)} \partial_{x(c)} g_i(x)

is possibly non-zero.
Note that the sparsity pattern should be symmetric.

ok
**
If this calculation succeeded, *ok* is true.
Otherwise it is false.
{xrst_toc_hidden
   example/atomic_three/hes_sparsity.cpp
}
Examples
********
The file :ref:`atomic_three_hes_sparsity.cpp-name` contains an example and test
that uses this routine.

{xrst_end atomic_three_hes_sparsity}