NAG Library Routine Document

g22znf (optget)

1

Purpose

2

Specification

3

Description

4

References

5

Arguments

1:     $\mathbf{handle}$ – Type (c_ptr)Input

On entry: the G22 handle which must have been initialized by one of Chapter G22's initialization routines.

2:     $\mathbf{optstr}$ – Character(*)Input

On entry: a string identifying the option and, where required, the instance identifier.

identify

Returns a string description of the G22 handle supplied in handle. See Section 9 for more details.

option

Returns the value of option. If there are multiple instances of option, the value of the first is returned. If not all instances of option have the same value, $\mathbf{ifail}=\mathbf{124}$ is returned.

$\mathit{option}:\mathit{instance\; identifier}$

Returns the value of a single instance of option.

optstr is case insensitive and option and instance identifier may consist of one or more tokens separated by white space.

See the documentation of the individual Chapter G22 routines for details of valid values for option and instance identifier.

3:     $\mathbf{ivalue}$ – IntegerOutput

On exit: if $\mathbf{optype}=1$, option identifies an integer-valued optional parameter and ivalue holds its current value.

4:     $\mathbf{rvalue}$ – Real (Kind=nag_wp)Output

On exit: if $\mathbf{optype}=2$, option identifies a real-valued optional parameter and rvalue holds its current value.

5:     $\mathbf{cvalue}$ – Character(*)Output

Note: the string returned in cvalue will never exceed $40$ characters in length.

On exit: if $\mathbf{optype}=3$, option identifies a character-valued optional parameter and cvalue holds its current value.

6:     $\mathbf{optype}$ – IntegerOutput

On exit: indicates whether option is an integer, real or character-valued optional parameter and hence which of ivalue, rvalue or cvalue holds the current value.

$\mathbf{optype}=1$

option is an integer-valued optional parameter; its current value has been returned in ivalue.

$\mathbf{optype}=2$

option is a real-valued optional parameter; its current value has been returned in rvalue.

$\mathbf{optype}=3$

option is a character-valued optional parameter; its current value has been returned in cvalue.

7:     $\mathbf{ifail}$ – 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

$\mathbf{ifail}=11$

handle has not been initialized or is corrupt.

$\mathbf{ifail}=12$

handle is not a G22 handle.

$\mathbf{ifail}=21$

On entry, option was not recognized: $\mathbf{optstr}=〈\mathit{\text{value}}〉$.

$\mathbf{ifail}=22$

On entry, option is not readable: $\mathbf{optstr}=〈\mathit{\text{value}}〉$.

$\mathbf{ifail}=51$

On entry, option is a character optional parameter, but cvalue is too short to hold the stored value. The minimum number of characters to store the value is returned in ivalue. The value returned in cvalue will be truncated.

$\mathbf{ifail}=121$

Invalid instance identifier for option.
On entry, $\mathbf{optstr}=〈\mathit{\text{value}}〉$.

$\mathbf{ifail}=122$

Numeric instance identifier is out of range.
On entry, $\mathit{instance\; identifier}=〈\mathit{\text{value}}〉$.
Constraint: $〈\mathit{\text{value}}〉\le \mathit{instance\; identifier}$ and $\mathit{instance\; identifier}\le 〈\mathit{\text{value}}〉$.

$\mathbf{ifail}=123$

On entry, option cannot have an associated instance identifier. The supplied instance identifier was ignored.
$\mathbf{optstr}=〈\mathit{\text{value}}〉$.

$\mathbf{ifail}=124$

option has multiple instances. Information from the first instance has been returned.

$\mathbf{ifail}=-99$

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