Note: please be advised that this routine is classed as ‘experimental’ and its interface may be developed further in the future. Please see
Section 4 in How to Use the NAG Library
for further information.
The routine may be called by the names g22znf or nagf_blgm_optget.
g22znf can only be called on G22 handles. It can be used to query the current values of optional parameters and will return either an integer, real or character value dependent upon the type associated with the optional parameter being queried.
The optional parameter of interest is presented as a character string of the form ‘’
In cases where an optional parameter may have multiple instances in a particular G22 handle an instance identifier can be specified. This is presented using the form ‘’. In such cases, if the instance identifier is omitted, the value of the first instance is returned. If the value of optional parameter is not the same for all instances and an instance identifier is omitted, a warning is raised.
Information relating to available option names, their corresponding valid values, whether the use of an instance identifier may be appropriate and what form it can take is given in the individual routine documents.
1: – Type (c_ptr)Input
On entry: the G22 handle which must have been initialized by one of Chapter G22's initialization routines.
2: – Character(*)Input
On entry: a string identifying the option and, where required, the instance identifier.
Returns a string description of the G22 handle supplied in handle. See Section 9 for more details.
Returns the value of . If there are multiple instances of , the value of the first is returned. If not all instances of have the same value, is returned.
Returns the value of a single instance of .
optstr is case insensitive and 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 and instance identifier.
3: – IntegerOutput
On exit: if , identifies an integer-valued optional parameter and ivalue holds its current value.
4: – Real (Kind=nag_wp)Output
On exit: if , identifies a real-valued optional parameter and rvalue holds its current value.
5: – Character(*)Output
Note: the string returned in cvalue will never exceed characters in length.
On exit: if , identifies a character-valued optional parameter and cvalue holds its current value.
6: – IntegerOutput
On exit: indicates whether is an integer, real or character-valued optional parameter and hence which of ivalue, rvalue or cvalue holds the current value.
is an integer-valued optional parameter; its current value has been returned in ivalue.
is a real-valued optional parameter; its current value has been returned in rvalue.
is a character-valued optional parameter; its current value has been returned in cvalue.
7: – IntegerInput/Output
On entry: ifail must be set to , or to set behaviour on detection of an error; these values have no effect when no error is detected.
A value of causes the printing of an error message and program execution will be halted; otherwise program execution continues. A value of means that an error message is printed while a value of means that it is not.
If halting is not appropriate, the value or is recommended. If message printing is undesirable, then the value is recommended. Otherwise, the value is recommended. When the value or is used it is essential to test the value of ifail on exit.
On exit: unless the routine detects an error or a warning has been flagged (see Section 6).
6Error Indicators and Warnings
If on entry or , explanatory error messages are output on the current error message unit (as defined by x04aaf).
On entry, 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.
Invalid instance identifier for . On entry, .
Numeric instance identifier is out of range. On entry, . Constraint: and .
On entry, cannot have an associated instance identifier. The supplied instance identifier was ignored.
has multiple instances. Information from the first instance has been returned.
An unexpected error has been triggered by this routine. Please
See Section 7 in the Introduction to the NAG Library FL Interface for further information.
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.
Dynamic memory allocation failed.
See Section 9 in the Introduction to the NAG Library FL Interface for further information.
8Parallelism and Performance
Background information to multithreading can be found in the Multithreading documentation.
g22znf is not threaded in any implementation.
When optstr is set to identify, the following return values are possible: