# NAG Library Function Document

## 1Purpose

nag_mip_opt_set (h02zkc) either initializes or resets the optional parameter arrays or sets a single optional parameter for supported problem solving functions in Chapter h.
Currently, only nag_mip_sqp (h02dac) is supported.

## 2Specification

 #include #include
 void nag_mip_opt_set (const char *optstr, Integer iopts[], Integer liopts, double opts[], Integer lopts, NagError *fail)

## 3Description

nag_mip_opt_set (h02zkc) 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 $\text{}=\mathit{optval}$’; alphabetic characters can be supplied in either upper or lower case. Both option and $\mathit{optval}$ may consist of one or more tokens separated by white space. The tokens that comprise $\mathit{optval}$ 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 $\mathit{optval}$ 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 function is called and before any options are queried using nag_mip_opt_get (h02zlc). To initialize the optional parameter arrays iopts and opts for a specific problem solving function, the option Initialize is used with optval identifying the problem solving function to be called. For example, to initialize optional parameter arrays to be passed to nag_mip_sqp (h02dac), nag_mip_opt_set (h02zkc) is called as follows:
```nag_mip_opt_set("Initialize = h02dac", iopts, liopts, opts, lopts, &fail)
```
Information relating to available option names and their corresponding valid values is given in Section 11 in nag_mip_sqp (h02dac).

None.

## 5Arguments

1:    $\mathbf{optstr}$const char *Input
On entry: a string identifying the option to be set.
$\mathbf{Initialize}=\mathit{function name}$
Initialize the optional parameter arrays iopts and opts for use with function $\mathit{function name}$, where $\mathit{function name}$ is the short name associated with the function of interest.
$\mathbf{Defaults}$
Resets all options to their default values.
$\mathit{option}=\mathit{optval}$
See Section 11 in nag_mip_sqp (h02dac) 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:    $\mathbf{iopts}\left[{\mathbf{liopts}}\right]$IntegerCommunication Array
3:    $\mathbf{liopts}$IntegerInput
On entry: the length of the array iopts.
Constraint: unless otherwise stated in the documentation for a specific, supported, problem solving function, ${\mathbf{liopts}}\ge 200$.
4:    $\mathbf{opts}\left[{\mathbf{lopts}}\right]$doubleCommunication Array
5:    $\mathbf{lopts}$IntegerInput
On entry: the length of the array opts.
Constraint: unless otherwise stated in the documentation for a specific, supported, problem solving function, ${\mathbf{lopts}}\ge 100$.
6:    $\mathbf{fail}$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, ${\mathbf{liopts}}=〈\mathit{\text{value}}〉$.
Constraint: ${\mathbf{liopts}}\ge 〈\mathit{\text{value}}〉$.
On entry, ${\mathbf{lopts}}=〈\mathit{\text{value}}〉$.
Constraint: ${\mathbf{lopts}}\ge 〈\mathit{\text{value}}〉$.
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_FORMAT
On entry, could not convert the specified optval to an integer: ${\mathbf{optstr}}=〈\mathit{\text{value}}〉$.
On entry, could not convert the specified optval to a real: ${\mathbf{optstr}}=〈\mathit{\text{value}}〉$.
On entry, the expected delimiter ‘$=$’ was not found in optstr: ${\mathbf{optstr}}=〈\mathit{\text{value}}〉$.
NE_INVALID_OPTION
On entry, either the option arrays have not been initialized or they have been corrupted.
On entry, the optional parameter in optstr was not recognized: ${\mathbf{optstr}}=〈\mathit{\text{value}}〉$.
NE_INVALID_VALUE
On entry, the optval supplied for the character optional parameter is not valid.
${\mathbf{optstr}}=〈\mathit{\text{value}}〉$.
On entry, the optval supplied for the integer optional parameter is not valid.
${\mathbf{optstr}}=〈\mathit{\text{value}}〉$.
On entry, the optval supplied for the real optional parameter is not valid.
${\mathbf{optstr}}=〈\mathit{\text{value}}〉$.
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.
NE_NOT_FUN_NAME
On entry, attempting to initialize the optional parameter arrays but specified function name was not valid: $\text{name}=〈\mathit{\text{value}}〉$.

Not applicable.

## 8Parallelism and Performance

nag_mip_opt_set (h02zkc) is threaded by NAG for parallel execution in multithreaded implementations of the NAG Library.
Please consult the x06 Chapter Introduction for information on how to control and interrogate the OpenMP environment used within this function. Please also consult the Users' Note for your implementation for any additional implementation-specific information.