NAG Library Routine Document

M01ZBF

1  Purpose

2  Specification

3  Description

4  References

5  Parameters

1:     IPERM(M2) – INTEGER arrayInput/Output

On entry: elements M1 to M2 of IPERM must be set to values which are supposed to be a permutation of the integers M1 to M2. If they are a valid permutation, the routine exits with $\mathbf{IFAIL}=\mathbf{0}$.

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

2:     M1 – INTEGERInput

3:     M2 – INTEGERInput

On entry: the range of elements used in the array IPERM and the range of values in the permutation, as specified under IPERM.

Constraint: $0<\mathbf{M1}\le \mathbf{M2}$.

4:     IFAIL – INTEGERInput/Output

On entry: IFAIL must be set to $0$, $-1\text{ or }1$. If you are unfamiliar with this parameter you should refer to Section 3.3 in the Essential Introduction 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 parameter, 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,	$\mathbf{M2}<1$,
or	$\mathbf{M1}<1$,
or	$\mathbf{M1}>\mathbf{M2}$.

$\mathbf{IFAIL}=2$

Elements M1 to M2 of IPERM contain a value outside the range M1 to M2.

$\mathbf{IFAIL}=3$

Elements M1 to M2 of IPERM contain a repeated value.

7  Accuracy

8  Further Comments

9  Example

9.1  Program Text

Program Text (m01zbfe.f90)

9.2  Program Data

Program Data (m01zbfe.d)

9.3  Program Results

Program Results (m01zbfe.r)