NAG Library Function Document

nag_2d_shep_eval (e01shc)

1  Purpose

2  Specification

3  Description

4  References

5  Arguments

1:     m – IntegerInput

2:     x[m] – const doubleInput

3:     y[m] – const doubleInput

4:     f[m] – const doubleInput

On entry: m, x, y and f must be the same values as were supplied in the preceding call to nag_2d_shep_interp (e01sgc).

5:     iq[$\left(2\times \mathbf{m}+1\right)$] – const IntegerInput

On entry: must be unchanged from the value returned from a previous call to nag_2d_shep_interp (e01sgc).

6:     rq[$\left(6\times \mathbf{m}+5\right)$] – const doubleInput

On entry: must be unchanged from the value returned from a previous call to nag_2d_shep_interp (e01sgc).

7:     n – IntegerInput

On entry: $n$, the number of evaluation points.

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

8:     u[n] – const doubleInput

9:     v[n] – const doubleInput

On entry: the evaluation points $\left(u_{\mathit{i}},v_{\mathit{i}}\right)$, for $\mathit{i}=1,2,\dots ,n$.

10:   q[n] – doubleOutput

On exit: the values of the interpolant at $\left(u_{\mathit{i}},v_{\mathit{i}}\right)$, for $\mathit{i}=1,2,\dots ,n$. If any of these evaluation points lie outside the region of definition of the interpolant the corresponding entries in q are set to the largest machine representable number (see nag_real_largest_number (X02ALC)), and nag_2d_shep_eval (e01shc) returns with $\mathbf{fail}\mathbf{.}\mathbf{code}=$ NE_BAD_INTERPOLANT.

11:   qx[n] – doubleOutput

12:   qy[n] – doubleOutput

On exit: the values of the partial derivatives of the interpolant $Q\left(x,y\right)$ at $\left(u_{\mathit{i}},v_{\mathit{i}}\right)$, for $\mathit{i}=1,2,\dots ,n$. If any of these evaluation points lie outside the region of definition of the interpolant, the corresponding entries in qx and qy are set to the largest machine representable number (see nag_real_largest_number (X02ALC)), and nag_2d_shep_eval (e01shc) returns with $\mathbf{fail}\mathbf{.}\mathbf{code}=$ NE_BAD_INTERPOLANT.

13:   fail – NagError *Input/Output

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

6  Error Indicators and Warnings

NE_BAD_INTERPOLANT

On entry, at least one evaluation point lies outside the region of definition of the interpolant. At all such points the corresponding values in q, qx and qy have been set to $\mathbf{nag\_real\_largest\_number}=⟨\mathit{\text{value}}⟩$.

NE_BAD_PARAM

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

NE_INT

On entry, $\mathbf{m}=⟨\mathit{\text{value}}⟩$.
Constraint: $\mathbf{m}\ge 6$.

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

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_ARRAY

On entry, values in iq appear to be invalid. Check that iq has not been corrupted between calls to nag_2d_shep_interp (e01sgc) and nag_2d_shep_eval (e01shc).

On entry, values in rq appear to be invalid. Check that rq has not been corrupted between calls to nag_2d_shep_interp (e01sgc) and nag_2d_shep_eval (e01shc).

7  Accuracy

8  Parallelism and Performance

9  Further Comments

10  Example