NAG AD Library
e02bc_a1w_f (dim1_spline_deriv_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

e02bc_a1w_f is the adjoint version of the primal routine e02bcf.

2 Specification

Fortran Interface
Subroutine e02bc_a1w_f ( ad_handle, ncap7, lamda, c, x, left, s, ifail)
Integer, Intent (In) :: ncap7, left
Integer, Intent (Inout) :: ifail
Type (nagad_a1w_w_rtype), Intent (In) :: lamda(ncap7), c(ncap7), x
Type (nagad_a1w_w_rtype), Intent (Out) :: s(4)
Type (c_ptr), Intent (Inout) :: ad_handle
C++ Header Interface
#include <nagad.h>
void e02bc_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, const Integer &left, nagad_a1w_w_rtype s[], Integer &ifail)
The routine may be called by the names e02bc_a1w_f or nagf_fit_dim1_spline_deriv_a1w. The corresponding t1w and p0w variants of this routine are also available.

3 Description

e02bc_a1w_f is the adjoint version of the primal routine e02bcf.
e02bcf evaluates a cubic spline and its first three derivatives from its B-spline representation. For further information see Section 3 in the documentation for e02bcf.

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
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, e02bc_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: xType (nagad_a1w_w_rtype) Input
6: left – Integer Input
7: s(4) – Type (nagad_a1w_w_rtype) array Output
8: ifail – Integer Input/Output

6 Error Indicators and Warnings

e02bc_a1w_f preserves all error codes from e02bcf 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

e02bc_a1w_f is not threaded in any implementation.

9 Further Comments


10 Example

The following examples are variants of the example for e02bcf, 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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