g02zkf either initializes or resets the optional parameter arrays or sets a single optional parameter for supported problem solving routines in Chapter G02. Currently, only g02qgf is supported.

2 Specification

Fortran Interface

Subroutine g02zkf (

optstr, iopts, liopts, opts, lopts, ifail)

Integer, Intent (In)	::	liopts, lopts
Integer, Intent (Inout)	::	iopts(liopts), ifail
Real (Kind=nag_wp), Intent (Inout)	::	opts(lopts)
Character (*), Intent (In)	::	optstr

C Header Interface

#include <nag.h>

void	g02zkf_ (const char optstr, Integer iopts[], const Integer liopts, double opts[], const Integer lopts, Integer ifail, const Charlen length_optstr)

The routine may be called by the names g02zkf or nagf_correg_optset.

3 Description

g02zkf has three purposes: to initialize optional parameter arrays, to reset all optional parameters to their default values or to set a single optional parameter to a user-supplied value.

Optional parameters and their values are, in general, presented as a character string, optstr, of the form ‘option

= optval

’; alphabetic characters can be supplied in either upper or lower case. Both option and

optval

may consist of one or more tokens separated by white space. The tokens that comprise

optval

will normally be either an integer, real or character value as defined in the description of the specific optional argument. In addition all optional parameters can take an

optval

DEFAULT which resets the optional parameter to its default value.

It is imperative that optional parameter arrays are initialized before any options are set, before the relevant problem solving routine is called and before any options are queried using g02zlf. To initialize the optional parameter arrays iopts and opts for a specific problem solving routine, the option Initialize is used with

value

identifying the problem solving routine to be called. For example, to initialize optional parameter arrays to be passed to g02qgf, g02zkf is called as follows:

Call g02zkf('Initialize = g02qgf', iopts, liopts, opts, lopts, ifail)

Note that the routine name may be abbreviated to just the first five letters of the ‘short’ name, or by omitting the nagf_ or correg_ prefixes of the ‘long’ name. So the above may be equivalently specified as 'Initialize = g02qg' or 'Initialize = quantile_linreg'.

Information relating to available option names and their corresponding valid values is given in Section 12 in g02qgf.

4 References

None.

5 Arguments

1: $optstr$ – Character(*) Input

On entry: a string identifying the option to be set.

$Initialize = routine name$: Initialize the optional parameter arrays iopts and opts for use with routine $routine name$ , where $routine name$ is the name of the problem solving routine you wish to use.
$Defaults$: Resets all options to their default values.

$option = optval$: See Section 12 in g02qgf for details of valid values for option and optval. The equals sign ( $=$ ) delimiter must be used to separate the option from its optval value.

optstr is case insensitive. Each token in the option and optval component must be separated by at least one space.

2: $iopts (liopts)$ – Integer array Communication Array

On entry: optional parameter array.

If optstr has the form

Initialize = routine name

, the contents of iopts need not be set.

Otherwise, iopts must not have been altered since the last call to g02zkf, g02zlf or the selected problem solving routine.

On exit: dependent on the contents of optstr, either an initialized, reset or updated version of the optional parameter array.

3: $liopts$ – Integer Input

On entry: the length of the array iopts.

Constraint: unless otherwise stated in the documentation for a specific, supported, problem solving routine,

liopts \geq 100

4: $opts (lopts)$ – Real (Kind=nag_wp) array Communication Array

On entry: optional parameter array.

If optstr has the form

Initialize = routine name

, the contents of opts need not be set.

Otherwise, opts must not have been altered since the last call to g02zkf, g02zlf or the selected problem solving routine.

On exit: dependent on the contents of optstr, either an initialized, reset or updated version of the optional parameter array.

5: $lopts$ – Integer Input

On entry: the length of the array opts.

Constraint: unless otherwise stated in the documentation for a specific, supported, problem solving routine,

lopts \geq 100

6: $ifail$ – Integer Input/Output

On entry: ifail must be set to

0

- 1

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

1

is recommended. If message printing is undesirable, then the value

1

is recommended. Otherwise, the value

0

is recommended. When the value $- 1$ or $1$ is used it is essential to test the value of ifail on exit.

On exit:

ifail = 0

unless the routine detects an error or a warning has been flagged (see Section 6).

6 Error Indicators and Warnings

If on entry

ifail = 0

- 1

, explanatory error messages are output on the current error message unit (as defined by x04aaf).

Errors or warnings detected by the routine:

$ifail = 11$: On entry, the option supplied in optstr was not recognized: $optstr = 〈value〉$ .

$ifail = 12$: On entry, the expected delimiter ‘ $=$ ’ was not found in optstr: $optstr = 〈value〉$ .

$ifail = 13$: On entry, could not convert the specified optval to an integer: $optstr = 〈value〉$ .

On entry, could not convert the specified optval to a real: $optstr = 〈value〉$ .

$ifail = 14$: On entry, attempting to initialize the optional parameter arrays but specified routine name was not valid: $name = 〈value〉$ .

$ifail = 15$: On entry, the optval supplied for the integer optional parameter is not valid.
$optstr = 〈value〉$ .

$ifail = 16$: On entry, the optval supplied for the real optional parameter is not valid.
$optstr = 〈value〉$ .

$ifail = 17$: On entry, the optval supplied for the character optional parameter is not valid.
$optstr = 〈value〉$ .

$ifail = 21$: On entry, either the option arrays have not been initialized or they have been corrupted.

$ifail = 31$: On entry, $liopts = 〈value〉$ .
Constraint: $liopts \geq 〈value〉$ .

$ifail = 51$: On entry, $lopts = 〈value〉$ .
Constraint: $lopts \geq 〈value〉$ .

$ifail = - 99$: 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.

$ifail = - 399$: 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.

$ifail = - 999$: Dynamic memory allocation failed.
See Section 9 in the Introduction to the NAG Library FL Interface for further information.

7 Accuracy

Not applicable.

8 Parallelism and Performance

g02zkf is not threaded in any implementation.

9 Further Comments

None.

10 Example

See the example programs associated with the problem solving routine you wish to use for a demonstration of how to use g02zkf to initialize option arrays and set options.

NAG Library Manual, Mark 27

Interfaces: FL CL CPP AD

NAG FL Interface Introduction

G02 (Correg) Chapter Contents

G02 (Correg) Chapter Introduction

g02zk: FL CL CPP AD

NAG FL Interfaceg02zkf (optset)

▸▿ Contents

1 Purpose