NAG AD Library
e02bb_a1w_f (dim1_spline_eval_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

E02 (Fit) Chapter Contents

E02 (Fit) Chapter Introduction (FL)

e02bb: 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

e02bb_a1w_f is the adjoint version of the primal routine e02bbf.

2 Specification

Fortran Interface

Subroutine e02bb_a1w_f (

ad_handle, ncap7, lamda, c, x, s, ifail)

Integer, Intent (In)	::	ncap7
Integer, Intent (Inout)	::	ifail
Type (nagad_a1w_w_rtype), Intent (In)	::	lamda(ncap7), c(ncap7), x
Type (nagad_a1w_w_rtype), Intent (Out)	::	s
Type (c_ptr), Intent (Inout)	::	ad_handle

C++ Header Interface

#include <nagad.h>

void e02bb_a1w_f_ (

void *&ad_handle, const Integer &ncap7, const nagad_a1w_w_rtype lamda[], const nagad_a1w_w_rtype c[], const nagad_a1w_w_rtype &x, nagad_a1w_w_rtype &s, Integer &ifail)

The routine may be called by the names e02bb_a1w_f or nagf_fit_dim1_spline_eval_a1w. The corresponding t1w and p0w variants of this routine are also available.

3 Description

e02bb_a1w_f is the adjoint version of the primal routine e02bbf.

e02bbf evaluates a cubic spline from its B-spline representation. For further information see Section 3 in the documentation for e02bbf.

4 References

Cox M G (1972) The numerical evaluation of B-splines J. Inst. Math. Appl. 10 134–149

Cox M G (1978) The numerical evaluation of a spline from its B-spline representation J. Inst. Math. Appl. 21 135–143

Cox M G and Hayes J G (1973) Curve fitting: a guide and suite of algorithms for the non-specialist user NPL Report NAC26 National Physical Laboratory

de Boor C (1972) On calculating with B-splines J. Approx. Theory 6 50–62

5 Arguments

In addition to the arguments present in the interface of the primal routine, e02bb_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: ncap7 – Integer Input
3: lamda(ncap7) – Type (nagad_a1w_w_rtype) array Input
4: c(ncap7) – Type (nagad_a1w_w_rtype) array Input
5: x – Type (nagad_a1w_w_rtype) Input
6: s – Type (nagad_a1w_w_rtype) Output
7: ifail – Integer Input/Output

6 Error Indicators and Warnings

e02bb_a1w_f preserves all error codes from e02bbf 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.