NAG C Library Function Document

nag_monotonic_interpolant (e01bec)

1

Purpose

2

Specification

3

Description

4

References

5

Arguments

1:    $\mathbf{n}$ – IntegerInput

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

Constraint: $\mathbf{n}\ge 2$.

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

On entry: $\mathbf{x}\left[\mathit{r}\right]$ must be set to $x_{\mathit{r}}$, the $\mathit{r}$th value of the independent variable (abscissa), for $\mathit{r}=0,1,\dots ,n-1$.

Constraint: $\mathbf{x}\left[r\right]<\mathbf{x}\left[r+1\right]$.

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

On entry: $\mathbf{f}\left[\mathit{r}\right]$ must be set to $f_{\mathit{r}}$, the $\mathit{r}$th value of the dependent variable (ordinate), for $\mathit{r}=0,1,\dots ,n-1$.

4:    $\mathbf{d}\left[\mathbf{n}\right]$ – doubleOutput

On exit: estimates of derivatives at the data points. $\mathbf{d}\left[r\right]$ contains the derivative at $\mathbf{x}\left[r\right]$.

5:    $\mathbf{fail}$ – 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_INT_ARG_LT

On entry, $\mathbf{n}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{n}\ge 2$.

NE_NOT_MONOTONIC

On entry, $\mathbf{x}\left[r-1\right]\ge \mathbf{x}\left[r\right]$ for $r=〈\mathit{value}〉$: $\mathbf{x}\left[r-1\right]$, $\mathbf{x}\left[r\right]=〈\mathit{values}〉$.
The values of $\mathbf{x}\left[\mathit{r}\right]$, for $\mathit{r}=0,1,\dots ,n-1$, are not in strictly increasing order.

7

Accuracy

8

Parallelism and Performance

9

Further Comments

e01bfc (n, x, f, d, m, px, pf, &fail)

10

Example

10.1

Program Text

Program Text (e01bece.c)

10.2

Program Data

Program Data (e01bece.d)

10.3

Program Results

Program Results (e01bece.r)