NAG Library Function Document

nag_5d_shep_eval (e01tnc)

1  Purpose

2  Specification

3  Description

4  References

5  Arguments

1:     m – IntegerInput

On entry: must be the same value supplied for argument m in the preceding call to nag_5d_shep_interp (e01tmc).

Constraint: $\mathbf{m}\ge 23$.

2:     x[$5\times \mathbf{m}$] – const doubleInput

Note: the $\left(i,j\right)$th element of the matrix $X$ is stored in $\mathbf{x}\left[\left(j-1\right)\times 5+i-1\right]$.

On entry: must be the same array supplied as argument x in the preceding call to nag_5d_shep_interp (e01tmc). It must remain unchanged between calls.

3:     f[m] – const doubleInput

On entry: must be the same array supplied as argument f in the preceding call to nag_5d_shep_interp (e01tmc). It must remain unchanged between calls.

4:     iq[$2\times \mathbf{m}+1$] – const IntegerInput

On entry: must be the same array returned as argument iq in the preceding call to nag_5d_shep_interp (e01tmc). It must remain unchanged between calls.

5:     rq[$21\times \mathbf{m}+11$] – const doubleInput

On entry: must be the same array returned as argument rq in the preceding call to nag_5d_shep_interp (e01tmc). It must remain unchanged between calls.

6:     n – IntegerInput

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

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

7:     xe[$5\times \mathbf{n}$] – const doubleInput

On entry: $\mathbf{xe}\left[\left(\mathit{i}-1\right)\times 5+0\right],\dots ,\mathbf{xe}\left[\left(\mathit{i}-1\right)\times 5+4\right]$ must be set to the evaluation point ${\mathbf{x}}_{\mathit{i}}$ , for $\mathit{i}=1,2,\dots ,n$.

8:     q[n] – doubleOutput

On exit: $\mathbf{q}\left[\mathit{i}-1\right]$ contains the value of the interpolant, at ${\mathbf{x}}_{\mathit{i}}$, 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_5d_shep_eval (e01tnc) returns with $\mathbf{fail}\mathbf{.}\mathbf{code}=$NE_BAD_POINT.

9:     qx[$5\times \mathbf{n}$] – doubleOutput

On exit: $\mathbf{qx}\left[\left(i-1\right)\times 5+j-1\right]$ contains the value of the partial derivatives with respect to ${\mathbf{x}}_j$ of the interpolant $Q\left(\mathbf{x}\right)$ at ${\mathbf{x}}_{\mathit{i}}$, for $\mathit{i}=1,2,\dots ,n$, and for each of the five partial derivatives $j=1,2,3,4,5$. If any of these evaluation points lie outside the region of definition of the interpolant, the corresponding entries in qx are set to the largest machine representable number (see nag_real_largest_number (X02ALC)), and nag_5d_shep_eval (e01tnc) returns with $\mathbf{fail}\mathbf{.}\mathbf{code}=$NE_BAD_POINT.

10:   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 and qx 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: $\mathbf{m}\ge 23$.

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_5d_shep_interp (e01tmc) and nag_5d_shep_eval (e01tnc).

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_5d_shep_interp (e01tmc) and nag_5d_shep_eval (e01tnc).

7  Accuracy

8  Further Comments

9  Example

9.1  Program Text

Program Text (e01tnce.c)

9.2  Program Data

Program Data (e01tnce.d)

9.3  Program Results

Program Results (e01tnce.r)