NAG Library Function Document

nag_3d_shep_eval (e01thc)

1  Purpose

2  Specification

3  Description

4  References

5  Arguments

1:     m – IntegerInput

2:     x[m] – const doubleInput

3:     y[m] – const doubleInput

4:     z[m] – const doubleInput

5:     f[m] – const doubleInput

On entry: m, x, y, z and f must be the same values as were supplied in the preceding call to nag_3d_shep_interp (e01tgc).

6:     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_3d_shep_interp (e01tgc).

7:     rq[$\left(10\times \mathbf{m}+7\right)$] – const doubleInput

On entry: must be unchanged from the value returned from a previous call to nag_3d_shep_interp (e01tgc).

8:     n – IntegerInput

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

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

9:     u[n] – const doubleInput

10:   v[n] – const doubleInput

11:   w[n] – const doubleInput

On entry: $\mathbf{u}\left[\mathit{i}-1\right]$, $\mathbf{v}\left[\mathit{i}-1\right]$, $\mathbf{w}\left[\mathit{i}-1\right]$ must be set to the evaluation point $\left(u_{\mathit{i}},v_{\mathit{i}},w_{\mathit{i}}\right)$, for $\mathit{i}=1,2,\dots ,n$.

12:   q[n] – doubleOutput

On exit: $\mathbf{q}\left[\mathit{i}-1\right]$ contains the value of the interpolant at $\left(u_{\mathit{i}},v_{\mathit{i}},w_{\mathit{i}}\right)$, 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_3d_shep_eval (e01thc) returns with $\mathbf{fail}\mathbf{.}\mathbf{code}=$ NE_BAD_POINT.

13:   qx[n] – doubleOutput

14:   qy[n] – doubleOutput

15:   qz[n] – doubleOutput

On exit: $\mathbf{qx}\left[\mathit{i}-1\right]$, $\mathbf{qy}\left[\mathit{i}-1\right]$, $\mathbf{qz}\left[\mathit{i}-1\right]$ contains the value of the partial derivatives of the interpolant $Q\left(x,y,z\right)$ at $\left(u_{\mathit{i}},v_{\mathit{i}},w_{\mathit{i}}\right)$, 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, qy and qz are set to the largest machine representable number (see nag_real_largest_number (X02ALC)), and nag_3d_shep_eval (e01thc) returns with $\mathbf{fail}\mathbf{.}\mathbf{code}=$ NE_BAD_POINT.

16:   fail – NagError *Input/Output

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

6  Error Indicators and Warnings

NE_BAD_PARAM

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

NE_BAD_POINT

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, qy and qz have been set to $\mathbf{nag\_real\_largest\_number}$: $\mathbf{nag\_real\_largest\_number}=⟨\mathit{\text{value}}⟩$.

NE_INT

On entry, $\mathbf{m}=⟨\mathit{\text{value}}⟩$.
Constraint: $\mathbf{m}\ge 10$.

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

NE_INT_ARRAY

On entry, values in iq appear to be invalid. Check that iq has not been corrupted between calls to nag_3d_shep_interp (e01tgc) and nag_3d_shep_eval (e01thc).

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_REAL_ARRAY

On entry, values in rq appear to be invalid. Check that rq has not been corrupted between calls to nag_3d_shep_interp (e01tgc) and nag_3d_shep_eval (e01thc).

7  Accuracy

8  Parallelism and Performance

9  Further Comments

10  Example