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## 1Purpose

e04ud is the AD Library version of the primal routine e04udf. Based (in the C++ interface) on overload resolution, e04ud can be used for primal, tangent and adjoint evaluation. It supports tangents and adjoints of first order.

## 2Specification

Fortran Interface
 Subroutine e04ud_AD_f ( ioptns, lwsav, iwsav, rwsav, inform)
 Integer, Intent (In) :: ioptns Integer, Intent (Inout) :: iwsav(610) Integer, Intent (Out) :: inform ADTYPE, Intent (Inout) :: rwsav(475) Logical, Intent (Inout) :: lwsav(120) 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 e04ud ( handle_t &ad_handle, const Integer &ioptns, logical lwsav[], Integer iwsav[], ADTYPE rwsav[], Integer &inform)
}
}
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

e04ud is the AD Library version of the primal routine e04udf.
e04udf may be used to supply optional parameters to e04ucf from an external file.
e04udf can also be used to supply optional parameters to e04uff. For further information see Section 3 in the documentation for e04udf.

## 5Arguments

In addition to the arguments present in the interface of the primal routine, e04ud 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.
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: ioptns – Integer Input
3: lwsav($120$) – logical array Communication Array
The arrays lwsav, iwsav and rwsav must not be altered between calls to any of the routines routine, routine, routine and routine.
4: iwsav($610$) – Integer array Communication Array
The arrays lwsav, iwsav and rwsav must not be altered between calls to any of the routines routine, routine, routine and routine.
5: rwsav($475$) – ADTYPE array Communication Array
The arrays lwsav, iwsav and rwsav must not be altered between calls to any of the routines routine, routine, routine and routine.
6: inform – Integer Output

## 6Error Indicators and Warnings

e04ud preserves all error codes from e04udf 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

e04ud is not threaded in any implementation.