NAG FL Interface
m01eaf (realvec_​rank_​rearrange)

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

1: $\mathbf{rv}\left(\mathbf{m2}\right)$ – Real (Kind=nag_wp) array Input/Output

On entry: elements m1 to m2 of rv must contain real values to be rearranged.

On exit: these values are rearranged into rank order. For example, if $\mathbf{irank}\left(i\right)=\mathbf{m1}$, then the initial value of $\mathbf{rv}\left(i\right)$ is moved to $\mathbf{rv}\left(\mathbf{m1}\right)$.

2: $\mathbf{m1}$ – Integer Input

3: $\mathbf{m2}$ – Integer Input

On entry: m1 and m2 must specify the range of the ranks supplied in irank and the elements of rv to be rearranged.

Constraint: $0<\mathbf{m1}\le \mathbf{m2}$.

4: $\mathbf{irank}\left(\mathbf{m2}\right)$ – Integer array Input/Output

On entry: elements m1 to m2 of irank must contain a permutation of the integers m1 to m2, which are interpreted as a vector of ranks.

On exit: used as internal workspace prior to being restored and hence is unchanged.

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

On entry: ifail must be set to $0$, $-1\text{ or }1$. If you are unfamiliar with this argument you should refer to Section 4 in the Introduction to the NAG Library FL Interface for details.

For environments where it might be inappropriate to halt program execution when an error is detected, the value $-1\text{ or }1$ is recommended. If the output of error messages is undesirable, then the value $1$ is recommended. Otherwise, if you are not familiar with this argument, the recommended value is $0$. When the value $-\mathbf{1}\text{ or }\mathbf{1}$ 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, $\mathbf{m1}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{m1}\ge 1$.

On entry, $\mathbf{m1}=〈\mathit{\text{value}}〉$ and $\mathbf{m2}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{m1}\le \mathbf{m2}$.

On entry, $\mathbf{m2}=〈\mathit{\text{value}}〉$.
Constraint: $\mathbf{m2}\ge 1$.

$\mathbf{ifail}=2$

$\mathbf{irank}\left(\mathbf{m1}:\mathbf{m2}\right)$ does not contain a permutation of the integers m1 to m2. $\mathbf{irank}\left(I\right)$ contains an out-of-range value: $I=〈\mathit{\text{value}}〉$, $\mathbf{irank}\left(I\right)=〈\mathit{\text{value}}〉$.

$\mathbf{ifail}=3$

$\mathbf{irank}\left(\mathbf{m1}:\mathbf{m2}\right)$ does not contain a permutation of the integers m1 to m2. irank contains a repeated value: $〈\mathit{\text{value}}〉$.

$\mathbf{ifail}=-99$

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