NAG Library Function Document

nag_2d_spline_ts_eval_rect (e02jfc)

1  Purpose

2  Specification

3  Description

4  References

5  Arguments

1:     nxeval – IntegerInput

On entry: $n_x$, the number of values in the $x$ direction forming the mesh on which the spline is to be evaluated.

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

2:     nyeval – IntegerInput

On entry: $n_y$, the number of values in the $y$ direction forming the mesh on which the spline is to be evaluated.

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

3:     xevalm[nxeval] – const doubleInput

On entry: the $\left(x_i\right)$ values forming the mesh on which the spline is to be evaluated.

Constraint: for all $i$, $\mathbf{xevalm}\left[i-1\right]$ must lie inside, or on the boundary of, the spline's bounding box as determined by nag_2d_spline_fit_ts_scat (e02jdc).

4:     yevalm[nyeval] – const doubleInput

On entry: the $\left(y_j\right)$ values forming the mesh on which the spline is to be evaluated.

Constraint: for all $j$, $\mathbf{yevalm}\left[j-1\right]$ must lie inside, or on the boundary of, the spline's bounding box as determined by nag_2d_spline_fit_ts_scat (e02jdc).

5:     coefs[$\mathit{dim}$] – const doubleCommunication Array

Note: the dimension, $\mathit{dim}$, of this array is dictated by the requirements of associated functions that must have been previously called. This array MUST be the same array passed as argument coefs in the previous call to nag_2d_spline_fit_ts_scat (e02jdc).

On entry: the computed spline coefficients as output from nag_2d_spline_fit_ts_scat (e02jdc).

6:     fevalm[$\mathbf{nxeval}\times \mathbf{nyeval}$] – doubleOutput

Note: the $\left(i,j\right)$th element of the matrix is stored in $\mathbf{fevalm}\left[\left(j-1\right)\times \mathbf{nxeval}+i-1\right]$.

On exit: if $\mathbf{fail}\mathbf{.}\mathbf{code}=$ NE_NOERROR on exit $\mathbf{fevalm}\left[\left(j-1\right)\times \mathbf{nxeval}+i-1\right]$ contains the computed spline value at $\left(x_i,y_j\right)$.

7:     iopts[$\mathit{dim}$] – const IntegerCommunication Array

Note: the dimension, $\mathit{dim}$, of this array is dictated by the requirements of associated functions that must have been previously called. This array MUST be the same array passed as argument iopts in the previous call to nag_fit_opt_set (e02zkc).

On entry: the contents of the array MUST NOT have been modified either directly or indirectly, by a call to nag_fit_opt_set (e02zkc), between calls to nag_2d_spline_fit_ts_scat (e02jdc) and nag_2d_spline_ts_eval_rect (e02jfc).

8:     opts[$\mathit{dim}$] – const doubleCommunication Array

Note: the dimension, $\mathit{dim}$, of this array is dictated by the requirements of associated functions that must have been previously called. This array MUST be the same array passed as argument opts in the previous call to nag_fit_opt_set (e02zkc).

On entry: the contents of the array MUST NOT have been modified either directly or indirectly, by a call to nag_fit_opt_set (e02zkc), between calls to nag_2d_spline_fit_ts_scat (e02jdc) and nag_2d_spline_ts_eval_rect (e02jfc).

9:     fail – NagError *Input/Output

The NAG error argument (see Section 3.6 in the Essential Introduction).

6  Error Indicators and Warnings

NE_ALLOC_FAIL

Dynamic memory allocation failed.

NE_BAD_PARAM

On entry, argument $⟨\mathit{\text{value}}⟩$ had an illegal value.

NE_INITIALIZATION

Option arrays are not initialized or are corrupted.

NE_INT

On entry, $\mathbf{nxeval}=⟨\mathit{\text{value}}⟩$.
Constraint: $\mathbf{nxeval}\ge 1$.

On entry, $\mathbf{nyeval}=⟨\mathit{\text{value}}⟩$.
Constraint: $\mathbf{nyeval}\ge 1$.

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.

NE_INVALID_SPLINE

The fitting routine has not been called, or the array of coefficients has been corrupted.

NE_POINT_OUTSIDE_RECT

On entry, $\mathbf{xevalm}\left[⟨\mathit{\text{value}}⟩\right]=⟨\mathit{\text{value}}⟩$ was outside the bounding box.
Constraint: $⟨\mathit{\text{value}}⟩\le \mathbf{xevalm}\left[i-1\right]\le ⟨\mathit{\text{value}}⟩$ for all $i$.

On entry, $\mathbf{yevalm}\left[⟨\mathit{\text{value}}⟩\right]=⟨\mathit{\text{value}}⟩$ was outside the bounding box.
Constraint: $⟨\mathit{\text{value}}⟩\le \mathbf{yevalm}\left[j-1\right]\le ⟨\mathit{\text{value}}⟩$ for all $j$.

7  Accuracy

8  Parallelism and Performance

9  Further Comments

10  Example