NAG Library Manual, Mark 27.1
Interfaces:  FL   CL   CPP   AD 
NAG AD Library Introduction
C05 (Roots) Chapter Contents
C05 (Roots) Chapter Introduction (FL)
c05qb:  FL   CL   CPP   AD 

NAG AD Library
c05qb_a1w_f (sys_func_easy_a1w)

Note: a1w denotes that first order adjoints are computed in working precision; this has the corresponding argument type nagad_a1w_w_rtype. Also available is the t1w (first order tangent linear) mode, the interface of which is implied by replacing a1w by t1w throughout this document. Additionally, the p0w (passive interface, as alternative to the FL interface) mode is available and can be inferred by replacing of active types by the corresponding passive types. The method of codifying AD implementations in the routine name and corresponding argument types is described in the NAG AD Library Introduction.
NAG Library Manual, Mark 27.1
Interfaces:  FL   CL   CPP   AD 
NAG AD Library Introduction
C05 (Roots) Chapter Contents
C05 (Roots) Chapter Introduction (FL)
c05qb:  FL   CL   CPP   AD 

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© The Numerical Algorithms Group Ltd. 2020
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1 Purpose

c05qb_a1w_f is the adjoint version of the primal routine c05qbf.

2 Specification

Fortran Interface
Subroutine c05qb_a1w_f ( ad_handle, fcn, n, x, fvec, xtol, iuser, ruser, ifail)
Integer, Intent (In) :: n
Integer, Intent (Inout) :: iuser(*), ifail
Type (nagad_a1w_w_rtype), Intent (In) :: xtol
Type (nagad_a1w_w_rtype), Intent (Inout) :: x(n), ruser(*)
Type (nagad_a1w_w_rtype), Intent (Out) :: fvec(n)
Type (c_ptr), Intent (Inout) :: ad_handle
External :: fcn
C++ Header Interface
#include <nagad.h>
void c05qb_a1w_f_ ( void *&ad_handle,
void (NAG_CALL fcn)(void *&ad_handle, const Integer &n, const nagad_a1w_w_rtype x[], nagad_a1w_w_rtype fvec[], Integer &iflag, Integer iuser[], nagad_a1w_w_rtype ruser[]),
const Integer &n, nagad_a1w_w_rtype x[], nagad_a1w_w_rtype fvec[], const nagad_a1w_w_rtype &xtol, Integer iuser[], nagad_a1w_w_rtype ruser[], Integer &ifail)
The routine may be called by the names c05qb_a1w_f or nagf_roots_sys_func_easy_a1w. The corresponding t1w and p0w variants of this routine are also available.

3 Description

c05qb_a1w_f is the adjoint version of the primal routine c05qbf.
c05qbf is an easy-to-use routine that finds a solution of a system of nonlinear equations by a modification of the Powell hybrid method. For further information see Section 3 in the documentation for c05qbf.

4 References

Moré J J, Garbow B S and Hillstrom K E (1980) User guide for MINPACK-1 Technical Report ANL-80-74 Argonne National Laboratory
Powell M J D (1970) A hybrid method for nonlinear algebraic equations Numerical Methods for Nonlinear Algebraic Equations (ed P Rabinowitz) Gordon and Breach

5 Arguments

In addition to the arguments present in the interface of the primal routine, c05qb_a1w_f 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.
1: ad_handle – Type (c_ptr) Input/Output
On entry: a handle to the AD configuration data object, as created by x10aa_a1w_f.
2: fcn – Subroutine External Procedure
The specification of fcn is:
Fortran Interface
Subroutine fcn ( ad_handle, n, x, fvec, iflag, iuser, ruser)
Integer, Intent (In) :: n
Integer, Intent (Inout) :: iuser(*), iflag
Type (nagad_a1w_w_rtype), Intent (In) :: x(n)
Type (nagad_a1w_w_rtype), Intent (Inout) :: ruser(*)
Type (nagad_a1w_w_rtype), Intent (Out) :: fvec(n)
Type (c_ptr), Intent (Inout) :: ad_handle
C++ Header Interface
#include <nagad.h>
void fcn ( void *&ad_handle, const Integer &n, const nagad_a1w_w_rtype x[], nagad_a1w_w_rtype fvec[], Integer &iflag, Integer iuser[], nagad_a1w_w_rtype ruser[])
1: ad_handle – Type (c_ptr) Input/Output
On entry: a handle to the AD configuration data object.
2: n – Integer Input
3: x – Type (nagad_a1w_w_rtype) array Input
4: fvec – Type (nagad_a1w_w_rtype) array Output
5: iuser – Integer array User Workspace
6: ruser – Type (nagad_a1w_w_rtype) array User Workspace
7: iflag – Integer Input/Output
3: n – Integer Input
4: x(n) – Type (nagad_a1w_w_rtype) array Input/Output
5: fvec(n) – Type (nagad_a1w_w_rtype) array Output
6: xtol – Type (nagad_a1w_w_rtype) Input
7: iuser(*) – Integer array User Workspace
8: ruser(*) – Type (nagad_a1w_w_rtype) array User Workspace
9: ifail – Integer Input/Output

6 Error Indicators and Warnings

c05qb_a1w_f preserves all error codes from c05qbf and in addition can return:
ifail=-89
An unexpected AD error has been triggered by this routine. Please contact NAG.
See Section 4.8.2 in the NAG AD Library Introduction for further information.
ifail=-899
Dynamic memory allocation failed for AD.
See Section 4.8.1 in the NAG AD Library Introduction for further information.

7 Accuracy

Not applicable.

8 Parallelism and Performance

c05qb_a1w_f is not threaded in any implementation.

9 Further Comments

None.

10 Example

The following examples are variants of the example for c05qbf, modified to demonstrate calling the NAG AD Library.

10.1 Adjoint mode (a1w)

LanguageSource FileDataResults
Fortranc05qb_a1w_fe.f90Nonec05qb_a1w_fe.r
C++c05qb_a1w_hcppe.cppNonec05qb_a1w_hcppe.r

10.2 Tangent mode (t1w)

LanguageSource FileDataResults
Fortranc05qb_t1w_fe.f90Nonec05qb_t1w_fe.r
C++c05qb_t1w_hcppe.cppNonec05qb_t1w_hcppe.r

10.3 Passive mode (p0w)

LanguageSource FileDataResults
Fortranc05qb_p0w_fe.f90Nonec05qb_p0w_fe.r
C++c05qb_p0w_hcppe.cppNonec05qb_p0w_hcppe.r
NAG Library Manual, Mark 27.1
Interfaces:  FL   CL   CPP   AD 
NAG AD Library Introduction
C05 (Roots) Chapter Contents
C05 (Roots) Chapter Introduction (FL)
c05qb:  FL   CL   CPP   AD 
© The Numerical Algorithms Group Ltd. 2020