NAG FL Interface
g10zaf (data_​order)

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

1: $\mathbf{weight}$ – Character(1) Input

On entry: indicates whether user-defined weights are to be used.

• If $\mathbf{weight}=\text{'W'}$, user-defined weights are to be used and must be supplied in wt.
• If $\mathbf{weight}=\text{'U'}$, the data is treated as unweighted.

Constraint: $\mathbf{weight}=\text{'W'}$ or $\text{'U'}$.

2: $\mathbf{n}$ – Integer Input

On entry: $n$, the number of observations.

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

3: $\mathbf{x}\left(\mathbf{n}\right)$ – Real (Kind=nag_wp) array Input

On entry: the values, $x_{\mathit{i}}$, for $\mathit{i}=1,2,\dots ,n$.

4: $\mathbf{y}\left(\mathbf{n}\right)$ – Real (Kind=nag_wp) array Input

On entry: the values $y_{\mathit{i}}$, for $\mathit{i}=1,2,\dots ,n$.

5: $\mathbf{wt}\left(*\right)$ – Real (Kind=nag_wp) array Input

Note: the dimension of the array wt must be at least $\mathbf{n}$ if $\mathbf{weight}=\text{'W'}$.

On entry: if $\mathbf{weight}=\text{'W'}$, wt must contain the $n$ weights. Otherwise wt is not referenced and unit weights are assumed.

Constraints:

• if $\mathbf{weight}=\text{'W'}$, $\mathbf{wt}\left(\mathit{i}\right)\ge 0.0$, for $\mathit{i}=1,2,\dots ,n$;
• if $\mathbf{weight}=\text{'W'}$, ${\sum }_{i=1}^n\mathbf{wt}\left(i\right)>0$.

6: $\mathbf{nord}$ – Integer Output

On exit: the number of distinct observations.

7: $\mathbf{xord}\left(\mathbf{n}\right)$ – Real (Kind=nag_wp) array Output

On exit: the first nord elements contain the ordered and distinct $x_i$.

8: $\mathbf{yord}\left(\mathbf{n}\right)$ – Real (Kind=nag_wp) array Output

On exit: the first nord elements contain the values $y^{\prime }$ corresponding to the values in xord.

9: $\mathbf{wtord}\left(\mathbf{n}\right)$ – Real (Kind=nag_wp) array Output

On exit: the first nord elements contain the values $w^{\prime }$ corresponding to the values of xord and yord.

10: $\mathbf{rss}$ – Real (Kind=nag_wp) Output

On exit: the within group sum of squares for tied observations.

11: $\mathbf{iwrk}\left(\mathbf{n}\right)$ – Integer array Workspace

12: $\mathbf{ifail}$ – Integer Input/Output

On entry: ifail must be set to $0$, $-1$ or $1$ to set behaviour on detection of an error; these values have no effect when no error is detected.

A value of $0$ causes the printing of an error message and program execution will be halted; otherwise program execution continues. A value of $-1$ means that an error message is printed while a value of $1$ means that it is not.

If halting is not appropriate, the value $-1$ or $1$ is recommended. If message printing is undesirable, then the value $1$ is recommended. Otherwise, the value $0$ is recommended. When the value $-\mathbf{1}$ or $\mathbf{1}$ is used it is essential to test the value of ifail on exit.

On exit: $\mathbf{ifail}=\mathbf{0}$ unless the routine detects an error or a warning has been flagged (see Section 6).

6 Error Indicators and Warnings

$\mathbf{ifail}=1$

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

On entry, $\mathbf{weight}=⟨\mathit{\text{value}}⟩$.
Constraint: $\mathbf{weight}=\text{'W'}$ or $\text{'U'}$.

$\mathbf{ifail}=2$

On entry, all weights are zero.

On entry, $i=⟨\mathit{\text{value}}⟩$ and $\mathbf{wt}\left(i\right)=⟨\mathit{\text{value}}⟩$.
Constraint: $\mathbf{wt}\left(i\right)\ge 0.0$.

$\mathbf{ifail}=-99$

An unexpected error has been triggered by this routine. Please contact NAG.

See Section 7 in the Introduction to the NAG Library FL Interface for further information.

$\mathbf{ifail}=-399$

Your licence key may have expired or may not have been installed correctly.

See Section 8 in the Introduction to the NAG Library FL Interface for further information.

$\mathbf{ifail}=-999$

Dynamic memory allocation failed.

See Section 9 in the Introduction to the NAG Library FL Interface for further information.

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example

10.1 Program Text

10.2 Program Data

10.3 Program Results