NAG AD Library Routine Document

s01ba_a1w_f (log_shifted_a1w)

Note: _a1w_ denotes that first order adjoints are computed in working precision; this has the corresponding argument type nagad_a1w_w_rtype. Further implementations, for example for higher order differentiation or using the tangent linear approach, may become available at later marks of the NAG AD Library. The method of codifying AD implementations in routine name and corresponding argument types is described in the NAG AD Library Introduction.

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NAG AD Library Manual, Mark 26

NAG Library Manual, Mark 26

NAG C Library Manual, Mark 26

NAG AD Library Introduction

Primal Routine s01baf

Primal NAG Library S Contents

Primal NAG Library S Chapter Introduction

▸▿ Contents

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

6 Error Indicators and Warnings

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example

1

Purpose

s01ba_a1w_f is the adjoint version of the primal routine s01baf .

2

Specification

Fortran Interface

Subroutine s01ba_a1w_f (

ad_handle, x, ret, ifail)

Integer, Intent (Inout)	::	ifail
Type (nagad_a1w_w_rtype), Intent (In)	::	x
Type (nagad_a1w_w_rtype), Intent (Out)	::	ret
Type (c_ptr), Intent (In)	::	ad_handle

C++ Header Interface

#include <nagad.h>

void s01ba_a1w_f_ (

void *&ad_handle, const nagad_a1w_w_rtype &x, nagad_a1w_w_rtype &ret, Integer &ifail)

3

Description

s01baf returns a value of the shifted logarithmic function,

\ln (1 + x)

, via the function name. For further information see Section 3 in the documentation for s01baf .

4

References

None.

5

Arguments

s01ba_a1w_f provides access to all the arguments available in the primal routine. There are also additional arguments specific to AD. A tooltip popup for each argument can be found by hovering over the argument name in Section 2 and a summary of the arguments are provided below:

ad_handle – a handle to the AD configuration data object, as created by x10aa_a1w_f.
x – the argument $x$ of the function.
ret – routine returns a value of the shifted logarithmic function, $\ln (1 + x)$ ..
ifail – on entry: ifail must be set to $0$ , $- 1 or 1$ . on exit: ifail = 0 unless the routine detects an error or a warning has been flagged (see Section 6).

6

Error Indicators and Warnings

s01ba_a1w_f preserves all error codes from s01baf and in addition can return:

$ifail = - 89$: An unexpected AD error has been triggered by this routine. Please contact NAG.
See Section 5.2 in the NAG AD Library Introduction for further information.

$ifail = - 899$: Dynamic memory allocation failed for AD.
See Section 5.1 in the NAG AD Library Introduction for further information.

7

Accuracy

Not applicable.

8

Parallelism and Performance

s01ba_a1w_f is not threaded in any implementation.

9

Further Comments

None.

10

Example

The following examples are variants of the example for s01baf , modified to demonstrate calling the NAG AD Library.

Language	Source File	Data	Results
Fortan	s01ba_a1w_fe.f90	s01ba_a1w_fe.d	s01ba_a1w_fe.r
C++	s01ba_a1w_hcppe.cpp	s01ba_a1w_hcppe.d	s01ba_a1w_hcppe.r
C	s01ba_a1w_hce.c	s01ba_a1w_hce.d	s01ba_a1w_hce.r