nag_glopt_opt_get (e05zlc) (PDF version)
e05 Chapter Contents
e05 Chapter Introduction
NAG C Library Manual

NAG Library Function Document

nag_glopt_opt_get (e05zlc)

+ Contents

    1  Purpose
    7  Accuracy
    9  Example

1  Purpose

nag_glopt_opt_get (e05zlc) is used to query the value of optional arguments available to supported problem solving functions in Chapter e05. Currently the following routines are supported:

2  Specification

#include <nag.h>
#include <nage05.h>
void  nag_glopt_opt_get (const char *optstr, Integer *ivalue, double *rvalue, char *cvalue, Integer lcvalue, Nag_VariableType *optype, const Integer iopts[], const double opts[], NagError *fail)

3  Description

nag_glopt_opt_get (e05zlc) is used to query the current values of options. It is necessary to initialize optional argument arrays using nag_glopt_opt_set (e05zkc) before any options are queried.
nag_glopt_opt_get (e05zlc) will normally return either an integer, real or character value dependent upon the type associated with the optional argument being queried. Some real and integer options also return additional information in cvalue. Whether the option queried is of integer, real or character type, and whether additional information is returned in cvalue, is indicated by the returned value of optype.
Information on optional argument names and whether these options are real, integer or character can be found in Section 11 in nag_glopt_bnd_pso (e05sac), nag_glopt_nlp_pso (e05sbc) and nag_glopt_nlp_multistart_sqp (e05ucc).

4  References

None.

5  Arguments

1:     optstrconst char *Input
On entry: a string identifying the option whose current value is required. See Section 11 in nag_glopt_bnd_pso (e05sac), nag_glopt_nlp_pso (e05sbc) and nag_glopt_nlp_multistart_sqp (e05ucc) for information on valid options. In addition, the following is a valid option:
Identify
nag_glopt_opt_get (e05zlc) returns in cvalue the function name supplied to nag_glopt_opt_set (e05zkc) when the optional argument arrays iopts and opts were initialized.
2:     ivalueInteger *Output
On exit: if the optional argument supplied in optstr is an integer valued argument, ivalue will hold its current value.
3:     rvaluedouble *Output
On exit: if the optional argument supplied in optstr is a real valued argument, rvalue will hold its current value.
4:     cvaluechar *Output
Note: the string returned in cvalue will never exceed minlcvalue,40 characters in length, including the terminating NULL character..
On exit: if the optional argument supplied in optstr is a character valued argument, cvalue will hold its current value. cvalue will also contain additional information for some integer and real valued arguments, as indicated by optype.
5:     lcvalueIntegerInput
On entry: length of the string cvalue. At most lcvalue-1 non-null characters will be written into cvalue.
Constraint: lcvalue>1.
6:     optypeNag_VariableType*Output
On exit: indicates whether the optional argument supplied in optstr is an integer, real or character valued argument and hence which of ivalue, rvalue or cvalue holds the current value.
optype=Nag_Integer
optstr is an integer valued optional argument, its current value has been returned in ivalue.
optype=Nag_Real
optstr is a real valued optional argument, its current value has been returned in rvalue.
optype=Nag_Character
optstr is a character valued optional argument, its current value has been returned in cvalue.
optype=Nag_Integer_Additional
optstr is an integer valued optional argument, its current value has been returned in ivalue. Additional information has been returned in cvalue.
optype=Nag_Real_Additional
optstr is a real valued optional argument, its current value has been returned in rvalue. Additional information has been returned in cvalue.
7:     iopts[dim]const IntegerCommunication Array
Note: the dimension, dim, of the array iopts must be at least liopts (see nag_glopt_opt_set (e05zkc)).
On entry: the contents of iopts MUST NOT have been altered between calls to nag_glopt_opt_set (e05zkc), nag_glopt_opt_get (e05zlc) or the selected problem solving function.
8:     opts[dim]const doubleCommunication Array
Note: the dimension, dim, of the array iopts must be at least lopts (see nag_glopt_opt_set (e05zkc)).
On entry: the contents of opts MUST NOT have been altered between calls to nag_glopt_opt_set (e05zkc), nag_glopt_opt_get (e05zlc) or the selected problem solving function.
9:     failNagError *Input/Output
The NAG error argument (see Section 3.6 in the Essential Introduction).

6  Error Indicators and Warnings

NE_ALLOC_FAIL
Dynamic memory allocation failed.
NE_BAD_PARAM
On entry, argument value had an illegal value.
NE_INT
On entry, lcvalue=value.
Constraint: lcvalue>1.
NE_INTERNAL_ERROR
An internal error has occurred in this function. Check the function call and any array sizes. If the call is correct then please contact NAG for assistance.
NE_INVALID_OPTION
On entry, the option in optstr has not been recognized.
The arrays iopts and opts have either not been initialized, have become corrupted, or are not compatible with this option setting function.
NW_TRUNCATED
On entry, optstr indicates a character optional argument, but cvalue is too short to hold the stored value. The returned value will be truncated.

7  Accuracy

Not applicable.

8  Further Comments

Some options have default values which are problem dependent. For example the option Maximum Iterations Completed for nag_glopt_bnd_pso (e05sac) has the default value 1000×ndim. If options such as this are queried before being set, or before the problem solving function has been called, they will return misleading information in ivalue or rvalue. In some cases, the value of cvalue will be set to DEFAULT to indicate that the real or integer valued optional argument supplied in optstr is at its default value.

9  Example

See the example programs associated with the problem solving function you wish to use for a demonstration of how to use nag_glopt_opt_get (e05zlc) to query options.

nag_glopt_opt_get (e05zlc) (PDF version)
e05 Chapter Contents
e05 Chapter Introduction
NAG C Library Manual

© The Numerical Algorithms Group Ltd, Oxford, UK. 2012