NAG Library Function Document

nag_2d_triang_bary_eval (e01ebc)

1

Purpose

2

Specification

3

Description

4

References

5

Arguments

1:    $\mathbf{m}$ – IntegerInput

On entry: $m$, the number of points to interpolate.

Constraint: $\mathbf{m}\ge 1$.

2:    $\mathbf{n}$ – IntegerInput

On entry: $n$, the number of data points. n must be unchanged from the previous call of nag_2d_triangulate (e01eac).

Constraint: $\mathbf{n}\ge 3$.

3:    $\mathbf{x}\left[\mathbf{n}\right]$ – const doubleInput

4:    $\mathbf{y}\left[\mathbf{n}\right]$ – const doubleInput

On entry: the coordinates of the $\mathit{r}$th data point, $\left(x_r,y_r\right)$, for $\mathit{r}=1,2,\dots ,n$. x and y must be unchanged from the previous call of nag_2d_triangulate (e01eac).

5:    $\mathbf{f}\left[\mathbf{n}\right]$ – const doubleInput

On entry: the function values $f_{\mathit{r}}$ at $\left(x_{\mathit{r}},y_{\mathit{r}}\right)$, for $\mathit{r}=1,2,\dots ,n$.

6:    $\mathbf{triang}\left[7\times \mathbf{n}\right]$ – const IntegerInput

On entry: the triangulation computed by the previous call of nag_2d_triangulate (e01eac). See Section 9 in nag_2d_triangulate (e01eac) for details of how the triangulation used is encoded in triang.

7:    $\mathbf{px}\left[\mathbf{m}\right]$ – const doubleInput

8:    $\mathbf{py}\left[\mathbf{m}\right]$ – const doubleInput

On entry: the coordinates $\left({\mathit{px}}_{\mathit{i}},{\mathit{py}}_{\mathit{i}}\right)$, for $\mathit{i}=1,2,\dots ,m$, at which interpolated function values are sought.

9:    $\mathbf{pf}\left[\mathbf{m}\right]$ – doubleOutput

On exit: the interpolated values $F\left({\mathit{px}}_{\mathit{i}},{\mathit{py}}_{\mathit{i}}\right)$, for $\mathit{i}=1,2,\dots ,m$.

10:  $\mathbf{fail}$ – NagError *Input/Output

The NAG error argument (see Section 3.7 in How to Use the NAG Library and its Documentation).

6

Error Indicators and Warnings

NE_ALLOC_FAIL

Dynamic memory allocation failed.
See Section 2.3.1.2 in How to Use the NAG Library and its Documentation for further information.

NE_BAD_PARAM

On entry, argument $〈\mathit{\text{value}}〉$ had an illegal value.

NE_INT

On entry, $\mathbf{m}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{m}\ge 1$.

On entry, $\mathbf{n}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{n}\ge 3$.

NE_INTERNAL_ERROR

An internal error has occurred in this function. Check the function call and any array sizes. If the call is correct then please contact NAG for assistance.
See Section 2.7.6 in How to Use the NAG Library and its Documentation for further information.

NE_NO_LICENCE

Your licence key may have expired or may not have been installed correctly.
See Section 2.7.5 in How to Use the NAG Library and its Documentation for further information.

NE_TRIANG_INVALID

On entry, the triangulation information held in the array triang does not specify a valid triangulation of the data points. triang has been corrupted since the call to nag_2d_triangulate (e01eac).

NW_EXTRAPOLATION

At least one evaluation point lies outside the nodal triangulation. For each such point the value returned in pf is that corresponding to a node on the closest boundary line segment.

7

Accuracy

8

Parallelism and Performance

9

Further Comments

10

Example