NAG AD Library
e01eb_a1w_f (dim2_triang_bary_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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1 Purpose

e01eb_a1w_f is the adjoint version of the primal routine e01ebf.

2 Specification

Fortran Interface
Subroutine e01eb_a1w_f ( ad_handle, m, n, x, y, f, triang, px, py, pf, ifail)
Integer, Intent (In) :: m, n, triang(7*n)
Integer, Intent (Inout) :: ifail
Type (nagad_a1w_w_rtype), Intent (In) :: x(n), y(n), f(n), px(m), py(m)
Type (nagad_a1w_w_rtype), Intent (Out) :: pf(m)
Type (c_ptr), Intent (Inout) :: ad_handle
C++ Header Interface
#include <nagad.h>
void e01eb_a1w_f_ ( void *&ad_handle, const Integer &m, const Integer &n, const nagad_a1w_w_rtype x[], const nagad_a1w_w_rtype y[], const nagad_a1w_w_rtype f[], const Integer triang[], const nagad_a1w_w_rtype px[], const nagad_a1w_w_rtype py[], nagad_a1w_w_rtype pf[], Integer &ifail)
The routine may be called by the names e01eb_a1w_f or nagf_interp_dim2_triang_bary_eval_a1w. The corresponding t1w and p0w variants of this routine are also available.

3 Description

e01eb_a1w_f is the adjoint version of the primal routine e01ebf.
e01ebf performs barycentric interpolation, at a given set of points, using a set of function values on a scattered grid and a triangulation of that grid computed by e01eaf. For further information see Section 3 in the documentation for e01ebf.

4 References

Cline A K and Renka R L (1984) A storage-efficient method for construction of a Thiessen triangulation Rocky Mountain J. Math. 14 119–139
Lawson C L (1977) Software for C1 surface interpolation Mathematical Software III (ed J R Rice) 161–194 Academic Press
Renka R L (1984) Algorithm 624: triangulation and interpolation of arbitrarily distributed points in the plane ACM Trans. Math. Software 10 440–442
Renka R L and Cline A K (1984) A triangle-based C1 interpolation method Rocky Mountain J. Math. 14 223–237

5 Arguments

In addition to the arguments present in the interface of the primal routine, e01eb_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: n – Integer Input
4: x(n) – Type (nagad_a1w_w_rtype) array Input
5: y(n) – Type (nagad_a1w_w_rtype) array Input
6: f(n) – Type (nagad_a1w_w_rtype) array Input
7: triang(7×n) – Integer array Input
8: px(m) – Type (nagad_a1w_w_rtype) array Input
9: py(m) – Type (nagad_a1w_w_rtype) array Input
10: pf(m) – Type (nagad_a1w_w_rtype) array Output
11: ifail – Integer Input/Output

6 Error Indicators and Warnings

e01eb_a1w_f preserves all error codes from e01ebf 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

e01eb_a1w_f is not threaded in any implementation.

9 Further Comments


10 Example

The following examples are variants of the example for e01ebf, 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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