NAG FL Interface
m01dzf (arbitrary_​rank)

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

1: $\mathbf{compar}$ – Logical Function, supplied by the user. External Procedure

compar must specify the relative ordering of any two data items; it must return .TRUE. if item i must come strictly after item j in the rank ordering.

The specification of compar is:

Fortran Interface

Function compar ( i, j) Logical :: compar Integer, Intent (In) :: i, j

C Header Interface

Nag_Boolean  compar_ (const Integer *i, const Integer *j)

C++ Header Interface

#include <nag.h> extern "C" { Nag_Boolean  compar_ (const Integer &i, const Integer &j) }

1: $\mathbf{i}$ – Integer Input

2: $\mathbf{j}$ – Integer Input

On entry: i and j identify the data items to be compared.

compar must either be a module subprogram USEd by, or declared as EXTERNAL in, the (sub)program from which m01dzf is called. Arguments denoted as Input must not be changed by this procedure.

2: $\mathbf{m1}$ – Integer Input

3: $\mathbf{m2}$ – Integer Input

On entry: m1 and m2 must specify the range of data items to be ranked, and the range of ranks to be assigned. Specifically, m01dzf ranks the data items identified by integers in the range m1 to m2, and assigns ranks in the range m1 to m2 which are stored in elements m1 to m2 of irank.

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

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

On exit: elements m1 to m2 of irank contain the ranks of the data items m1 to m2. Note that the ranks are in the range m1 to m2: thus, if item $i$ is first in the rank ordering, $\mathbf{irank}\left(i\right)$ contains m1.

5: $\mathbf{ifail}$ – 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, $\mathbf{m1}=〈\mathit{\text{value}}〉$.
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: $\mathbf{m2}\ge 1$.

$\mathbf{ifail}=-99$

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