NAG AD Library
f11bf_a1w_f (real_gen_basic_diag_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.
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1 Purpose

f11bf_a1w_f is the adjoint version of the primal routine f11bff.

2 Specification

Fortran Interface
Subroutine f11bf_a1w_f ( ad_handle, itn, stplhs, stprhs, anorm, sigmax, work, lwork, ifail)
Integer, Intent (In) :: lwork
Integer, Intent (Inout) :: ifail
Integer, Intent (Out) :: itn
Type (nagad_a1w_w_rtype), Intent (In) :: work(lwork)
Type (nagad_a1w_w_rtype), Intent (Out) :: stplhs, stprhs, anorm, sigmax
Type (c_ptr), Intent (Inout) :: ad_handle
C++ Header Interface
#include <nagad.h>
void f11bf_a1w_f_ ( void *&ad_handle, Integer &itn, nagad_a1w_w_rtype &stplhs, nagad_a1w_w_rtype &stprhs, nagad_a1w_w_rtype &anorm, nagad_a1w_w_rtype &sigmax, const nagad_a1w_w_rtype work[], const Integer &lwork, Integer &ifail)
The routine may be called by the names f11bf_a1w_f or nagf_sparse_real_gen_basic_diag_a1w. The corresponding t1w and p0w variants of this routine are also available.

3 Description

f11bf_a1w_f is the adjoint version of the primal routine f11bff.
f11bff is the third in a suite of three routines for the iterative solution of a real general (nonsymmetric) system of simultaneous linear equations (see Golub and Van Loan (1996)). f11bff returns information about the computations during an iteration and/or after this has been completed. The first routine of the suite, f11bdf, is a setup routine; the second routine, f11bef, is the iterative solver itself.
These three routines are suitable for the solution of large sparse general (nonsymmetric) systems of equations. For further information see Section 3 in the documentation for f11bff.

4 References

Golub G H and Van Loan C F (1996) Matrix Computations (3rd Edition) Johns Hopkins University Press, Baltimore

5 Arguments

In addition to the arguments present in the interface of the primal routine, f11bf_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: itn – Integer Output
3: stplhsType (nagad_a1w_w_rtype) Output
4: stprhsType (nagad_a1w_w_rtype) Output
5: anormType (nagad_a1w_w_rtype) Output
6: sigmaxType (nagad_a1w_w_rtype) Output
7: work(lwork) – Type (nagad_a1w_w_rtype) array Communication Array
8: lwork – Integer Input
9: ifail – Integer Input/Output

6 Error Indicators and Warnings

f11bf_a1w_f preserves all error codes from f11bff and in addition can return:
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.
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

f11bf_a1w_f is not threaded in any implementation.

9 Further Comments


10 Example

The following examples are variants of the example for f11bff, modified to demonstrate calling the NAG AD Library.

10.1 Adjoint mode (a1w)

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10.2 Tangent mode (t1w)

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10.3 Passive mode (p0w)

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