NAG AD Library
e01ba_a1w_f (dim1_spline_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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NAG Library Manual, Mark 27.1

Interfaces: FL CL CPP AD

NAG AD Library Introduction

E01 (Interp) Chapter Contents

E01 (Interp) Chapter Introduction (FL)

e01ba: FL CL CPP AD

▸▿ 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

10.1 Adjoint mode (a1w)

10.2 Tangent mode (t1w)

10.3 Passive mode (p0w)

1 Purpose

e01ba_a1w_f is the adjoint version of the primal routine e01baf.

2 Specification

Fortran Interface

Subroutine e01ba_a1w_f (

ad_handle, m, x, y, lamda, c, lck, wrk, lwrk, ifail)

Integer, Intent (In)	::	m, lck, lwrk
Integer, Intent (Inout)	::	ifail
Type (nagad_a1w_w_rtype), Intent (In)	::	x(m), y(m)
Type (nagad_a1w_w_rtype), Intent (Out)	::	lamda(lck), c(lck), wrk(lwrk)
Type (c_ptr), Intent (Inout)	::	ad_handle

C++ Header Interface

#include <nagad.h>

void e01ba_a1w_f_ (

void *&ad_handle, const Integer &m, const nagad_a1w_w_rtype x[], const nagad_a1w_w_rtype y[], nagad_a1w_w_rtype lamda[], nagad_a1w_w_rtype c[], const Integer &lck, nagad_a1w_w_rtype wrk[], const Integer &lwrk, Integer &ifail)

The routine may be called by the names e01ba_a1w_f or nagf_interp_dim1_spline_a1w. The corresponding t1w and p0w variants of this routine are also available.

3 Description

e01ba_a1w_f is the adjoint version of the primal routine e01baf.

e01baf determines a cubic spline interpolant to a given set of data. For further information see Section 3 in the documentation for e01baf.

4 References

Cox M G (1975) An algorithm for spline interpolation J. Inst. Math. Appl. 15 95–108

Cox M G (1977) A survey of numerical methods for data and function approximation The State of the Art in Numerical Analysis (ed D A H Jacobs) 627–668 Academic Press

5 Arguments

In addition to the arguments present in the interface of the primal routine, e01ba_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: m – Integer Input
3: x(m) – Type (nagad_a1w_w_rtype) array Input
4: y(m) – Type (nagad_a1w_w_rtype) array Input
5: lamda(lck) – Type (nagad_a1w_w_rtype) array Output
6: c(lck) – Type (nagad_a1w_w_rtype) array Output
7: lck – Integer Input
8: wrk(lwrk) – Type (nagad_a1w_w_rtype) array Workspace
9: lwrk – Integer Input
10: ifail – Integer Input/Output

6 Error Indicators and Warnings

e01ba_a1w_f preserves all error codes from e01baf 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.