NAG FL Interface
m01daf (realvec_​rank)

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

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

On entry: elements $\mathbf{m1}$ to $\mathbf{m2}$ of rv must contain real values to be ranked.

2: $\mathbf{m1}$ – Integer Input

On entry: the index of the first element of rv to be ranked.

Constraint: $\mathbf{m1}>0$.

3: $\mathbf{m2}$ – Integer Input

On entry: the index of the last element of rv to be ranked.

Constraint: $\mathbf{m2}\ge \mathbf{m1}$.

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

On entry: if $\mathbf{order}=\text{'A'}$, the values will be ranked in ascending (i.e., nondecreasing) order.

If $\mathbf{order}=\text{'D'}$, into descending order.

Constraint: $\mathbf{order}=\text{'A'}$ or $\text{'D'}$.

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

On exit: elements $\mathbf{m1}$ to $\mathbf{m2}$ of irank contain the ranks of the corresponding elements of rv. Note that the ranks are in the range m1 to m2: thus, if $\mathbf{rv}\left(i\right)$ is the first element in the rank order, $\mathbf{irank}\left(i\right)$ is set to m1.

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

On entry: ifail must be set to $0$, $\mathrm{-1}$ 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 $\mathrm{-1}$ means that an error message is printed while a value of $1$ means that it is not.

If halting is not appropriate, the value $\mathrm{-1}$ 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: $\mathbf{m2}\ge 1$.

$\mathbf{ifail}=2$

On entry, order has an illegal value: $\mathbf{order}=⟨\mathit{\text{value}}⟩$.

$\mathbf{ifail}=-99$

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