NAG Library Manual, Mark 27
Interfaces:  FL   CL   CPP   AD 
NAG AD Library Introduction
F08 (Lapackeig) Chapter Contents
F08 (Lapackeig) Chapter Introduction (FL)
f08ah:  FL   CL   CPP   AD 

NAG AD Library
f08ah_a1w_f (dgelqf_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 the routine name and corresponding argument types is described in the NAG AD Library Introduction.
NAG Library Manual, Mark 27
Interfaces:  FL   CL   CPP   AD 
NAG AD Library Introduction
F08 (Lapackeig) Chapter Contents
F08 (Lapackeig) Chapter Introduction (FL)
f08ah:  FL   CL   CPP   AD 

▸▿ Contents

© The Numerical Algorithms Group Ltd. 2019

1 Purpose

f08ah_a1w_f is the adjoint version of the primal routine f08ahf (dgelqf).

2 Specification

Fortran Interface
Subroutine f08ah_a1w_f ( ad_handle, m, n, a, lda, tau, work, lwork, ifail)
Integer, Intent (In) :: m, n, lda, lwork
Integer, Intent (Inout) :: ifail
Type (nagad_a1w_w_rtype), Intent (Inout) :: a(lda,*), tau(*)
Type (nagad_a1w_w_rtype), Intent (Out) :: work(max(1,lwork))
Type (c_ptr), Intent (In) :: ad_handle
C++ Header Interface
#include <nagad.h>
void f08ah_a1w_f_ ( void *&ad_handle, const Integer &m, const Integer &n, nagad_a1w_w_rtype a[], const Integer &lda, nagad_a1w_w_rtype tau[], nagad_a1w_w_rtype work[], const Integer &lwork, Integer &ifail)
The routine may be called by the names f08ah_a1w_f or nagf_lapackeig_dgelqf_a1w.

3 Description

f08ah_a1w_f is the adjoint version of the primal routine f08ahf (dgelqf).
f08ahf (dgelqf) computes the LQ factorization of a real m by n matrix. For further information see Section 3 in the documentation for f08ahf (dgelqf).

4 References

None.

5 Arguments

In addition to the arguments present in the interface of the primal routine, f08ah_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
On entry: a handle to the AD configuration data object, as created by x10aa_a1w_f.
2: m – Integer Input
3: n – Integer Input
4: a(lda, *) – Type (nagad_a1w_w_rtype) array Input/Output
5: lda – Integer Input
6: tau(*) – Type (nagad_a1w_w_rtype) array Output
7: work(max1,lwork) – Type (nagad_a1w_w_rtype) array Workspace
8: lwork – Integer Input
9: ifail – Integer Input/Output
On entry: must be set to 0, -1  or  1.
On exit: any errors are indicated as described in Section 6.

6 Error Indicators and Warnings

f08ah_a1w_f uses the standard NAG ifail mechanism. Any errors indicated via info values returned by f08ahf may be indicated with the same value returned by ifail. In addition, this routine may return:
ifail=-89
An unexpected AD error has been triggered by this routine. Please contact NAG.
See Section 4.5.2 in the NAG AD Library Introduction for further information.
ifail=-899
Dynamic memory allocation failed for AD.
See Section 4.5.1 in the NAG AD Library Introduction for further information.

7 Accuracy

Not applicable.

8 Parallelism and Performance

f08ah_a1w_f is not threaded in any implementation.

9 Further Comments

None.

10 Example

The following examples are variants of the example for f08ahf (dgelqf), modified to demonstrate calling the NAG AD Library.
LanguageSource FileDataResults
Fortranf08ah_a1w_fe.f90f08ah_a1w_fe.df08ah_a1w_fe.r
C++f08ah_a1w_hcppe.cppf08ah_a1w_hcppe.df08ah_a1w_hcppe.r
NAG Library Manual, Mark 27
Interfaces:  FL   CL   CPP   AD 
NAG AD Library Introduction
F08 (Lapackeig) Chapter Contents
F08 (Lapackeig) Chapter Introduction (FL)
f08ah:  FL   CL   CPP   AD 
© The Numerical Algorithms Group Ltd. 2019