# NAG C Library Function Document

## 1Purpose

nag_mip_opt_get (h02zlc) is used to query the value of optional parameters available to supported problem solving functions in Chapter h.
Currently, only nag_mip_sqp (h02dac) is supported.

## 2Specification

 #include #include
 void nag_mip_opt_get (const char *optstr, Integer *ivalue, double *rvalue, char *cvalue, Integer lcvalue, Nag_VariableType *optype, const Integer iopts[], const double opts[], NagError *fail)

## 3Description

nag_mip_opt_get (h02zlc) is used to query the current values of options. It is necessary to initialize optional parameter arrays using nag_mip_opt_set (h02zkc) before any options are queried.
nag_mip_opt_get (h02zlc) will normally return either an integer, real or character value dependent upon the type associated with the optional parameter 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 parameter names and whether these options are real, integer or character can be found in Section 11 in nag_mip_sqp (h02dac).

None.

## 5Arguments

1:    $\mathbf{optstr}$const char *Input
On entry: a string identifying the option whose current value is required. See Section 11 in nag_mip_sqp (h02dac) for information on valid options. In addition, the following is a valid option:
$\mathbf{Identify}$
nag_mip_opt_get (h02zlc) returns in cvalue the function name supplied to nag_mip_opt_set (h02zkc) when the optional parameter arrays iopts and opts were initialized.
2:    $\mathbf{ivalue}$Integer *Output
On exit: if the optional parameter supplied in optstr is an integer valued argument, ivalue will hold its current value.
3:    $\mathbf{rvalue}$double *Output
On exit: if the optional parameter supplied in optstr is a real valued argument, rvalue will hold its current value.
4:    $\mathbf{cvalue}$char *Output
Note: the string returned in cvalue will never exceed $\mathrm{min}\phantom{\rule{0.125em}{0ex}}\left({\mathbf{lcvalue}},41\right)$ characters in length (including the null terminator).
On exit: if the optional parameter 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:    $\mathbf{lcvalue}$IntegerInput
On entry: length of cvalue. At most ${\mathbf{lcvalue}}-1$ non-null characters will be written into cvalue.
Constraint: ${\mathbf{lcvalue}}>1$.
6:    $\mathbf{optype}$Nag_VariableType *Output
On exit: indicates whether the optional parameter supplied in optstr is an integer, real or character valued argument and hence which of ivalue, rvalue or cvalue holds the current value.
${\mathbf{optype}}=\mathrm{Nag_Integer}$
optstr is an integer valued optional parameter, its current value has been returned in ivalue.
${\mathbf{optype}}=\mathrm{Nag_Real}$
optstr is a real valued optional parameter, its current value has been returned in rvalue.
${\mathbf{optype}}=\mathrm{Nag_Character}$
optstr is a character valued optional parameter, its current value has been returned in cvalue.
${\mathbf{optype}}=\mathrm{Nag_Integer_Additional}$
optstr is an integer valued optional parameter, its current value has been returned in ivalue. Additional information has been returned in cvalue.
${\mathbf{optype}}=\mathrm{Nag_Real_Additional}$
optstr is a real valued optional parameter, its current value has been returned in rvalue. Additional information has been returned in cvalue.
7:    $\mathbf{iopts}\left[\mathit{dim}\right]$const IntegerCommunication Array
Note: the dimension, $\mathit{dim}$, of this array is dictated by the requirements of associated functions that must have been previously called. This array MUST be the same array passed as argument iopts in the previous call to nag_mip_opt_set (h02zkc).
8:    $\mathbf{opts}\left[\mathit{dim}\right]$const doubleCommunication Array
Note: the dimension, $\mathit{dim}$, of this array is dictated by the requirements of associated functions that must have been previously called. This array MUST be the same array passed as argument opts in the previous call to nag_mip_opt_set (h02zkc).
9:    $\mathbf{fail}$NagError *Input/Output
The NAG error argument (see Section 3.7 in How to Use the NAG Library and its Documentation).

## 6Error Indicators and Warnings

NE_ALLOC_FAIL
Dynamic memory allocation failed.
See Section 2.3.1.2 in How to Use the NAG Library and its Documentation for further information.
On entry, argument $〈\mathit{\text{value}}〉$ had an illegal value.
NE_INT
On entry, ${\mathbf{lcvalue}}=〈\mathit{\text{value}}〉$.
Constraint: ${\mathbf{lcvalue}}>1$.
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.
See Section 2.7.6 in How to Use the NAG Library and its Documentation for further information.
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.
NE_NO_LICENCE
Your licence key may have expired or may not have been installed correctly.
See Section 2.7.5 in How to Use the NAG Library and its Documentation for further information.
NW_TRUNCATED
On entry, optstr indicates a character optional parameter, but cvalue is too short to hold the stored value. The returned value will be truncated.

Not applicable.

## 8Parallelism and Performance

nag_mip_opt_get (h02zlc) is not threaded in any implementation.