NAG Library Routine Document

m01ecf (charvec_rank_rearrange)

1

Purpose

2

Specification

3

Description

4

References

5

Arguments

1:     $\mathbf{ch}\left(\mathbf{m2}\right)$ – Character(*) arrayInput/Output

On entry: elements m1 to m2 of ch must contain character data to be rearranged.

Constraint: the length of each element of ch must not exceed $255$.

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

2:     $\mathbf{m1}$ – IntegerInput

3:     $\mathbf{m2}$ – IntegerInput

On entry: the range of the ranks supplied in irank and the elements of ch to be rearranged.

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

4:     $\mathbf{irank}\left(\mathbf{m2}\right)$ – Integer arrayInput/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:     $\mathbf{ifail}$ – IntegerInput/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 3.4 in How to Use the NAG Library and its Documentation 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: $\mathbf{m2}\ge 1$.

$\mathbf{ifail}=2$

On entry, $\mathrm{len}\left(\mathbf{ch}\left(1\right)\right)=〈\mathit{\text{value}}〉$.
Constraint: $\mathrm{len}\left(\mathbf{ch}\left(1\right)\right)\le 255$.

$\mathbf{ifail}=3$

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

$\mathbf{ifail}=4$

$\mathbf{irank}\left(\mathbf{m1}:\mathbf{m2}\right)$ 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 3.9 in How to Use the NAG Library and its Documentation for further information.

$\mathbf{ifail}=-399$

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

See Section 3.8 in How to Use the NAG Library and its Documentation for further information.

$\mathbf{ifail}=-999$

Dynamic memory allocation failed.

See Section 3.7 in How to Use the NAG Library and its Documentation for further information.

7

Accuracy

8

Parallelism and Performance

9

Further Comments

10

Example

10.1

Program Text

Program Text (m01ecfe.f90)

10.2

Program Data

Program Data (m01ecfe.d)

10.3

Program Results

Program Results (m01ecfe.r)