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## 1Purpose

e05jh is the AD Library version of the primal routine e05jhf. Based (in the C++ interface) on overload resolution, e05jh can be used for primal, tangent and adjoint evaluation. It supports tangents and adjoints of first order.

## 2Specification

Fortran Interface
 Function e05jh_AD_f ( optstr, ichkopt, comm, lcomm, ifail)
 Integer, Intent (In) :: lcomm Integer, Intent (Inout) :: ifail Integer, Intent (Out) :: ichkopt ADTYPE, Intent (In) :: comm(lcomm) Character (*), Intent (In) :: optstr Type (c_ptr), Intent (Inout) :: ad_handle
Corresponding to the overloaded C++ function, the Fortran interface provides five routines with names reflecting the type used for active real arguments. The actual subroutine and type names are formed by replacing AD and ADTYPE in the above as follows:
C++ Interface
#include <dco.hpp>
namespace nag {
 void e05jh ( handle_t &ad_handle, const char *optstr, Integer &ichkopt, const ADTYPE comm[], const Integer &lcomm, Integer &ifail)
}
}
The function is overloaded on ADTYPE which represents the type of active arguments. ADTYPE may be any of the following types:
double,
dco::ga1s<double>::type,
dco::gt1s<double>::type

## 3Description

e05jh is the AD Library version of the primal routine e05jhf.
e05jhf is used to check if you have set an optional parameter of e05jbf. The initialization routine e05jaf must have been called before calling e05jhf. For further information see Section 3 in the documentation for e05jhf.

## 5Arguments

In addition to the arguments present in the interface of the primal routine, e05jh includes some arguments specific to AD.
A brief summary of the AD specific arguments is given below. For the remainder, links are provided to the corresponding argument from the primal routine. A tooltip popup for all arguments can be found by hovering over the argument name in Section 2 and in this section.
Note that the primal routine is a function whereas e05jh_a1w_f, is a subroutine, where the function value is returned in the additional output parameter, ichkopt.
On entry: a configuration object that holds information on the differentiation strategy. Details on setting the AD strategy are described in AD handle object in the NAG AD Library Introduction.
2: optstr – character Input
3: ichkopt – Integer Output
On exit: $\mathbf{ichkopt}=1$ if you have set the option of routine.
4: comm(lcomm) – ADTYPE array Communication Array
5: lcomm – Integer Input
6: ifail – Integer Input/Output

## 6Error Indicators and Warnings

e05jh preserves all error codes from e05jhf and in addition can return:
${\mathbf{ifail}}=-89$
See Error Handling in the NAG AD Library Introduction for further information.
${\mathbf{ifail}}=-199$
The routine was called using a strategy that has not yet been implemented.
See AD Strategies in the NAG AD Library Introduction for further information.
${\mathbf{ifail}}=-444$
A C++ exception was thrown.
The error message will show the details of the C++ exception text.
${\mathbf{ifail}}=-899$
Dynamic memory allocation failed for AD.
See Error Handling in the NAG AD Library Introduction for further information.

Not applicable.

## 8Parallelism and Performance

e05jh is not threaded in any implementation.