# NAG C Library Function Document

## 1Purpose

To supply optional parameters to nag_opt_nlp_revcomm (e04ufc) from an external file.

## 2Specification

 #include #include
 void nag_opt_nlp_revcomm_option_set_file (Nag_FileID fileid, Nag_Boolean lwsav[], Integer iwsav[], double rwsav[], NagError *fail)

## 3Description

nag_opt_nlp_revcomm_option_set_file (e04udc) may be used to supply values for optional parameters to nag_opt_nlp_revcomm (e04ufc). nag_opt_nlp_revcomm_option_set_file (e04udc) reads an external file and each line of the file defines a single optional parameter. It is only necessary to supply values for those arguments whose values are to be different from their default values.
Each optional parameter is defined by a single character string, consisting of one or more items. The items associated with a given option must be separated by spaces, or equals signs $\left[=\right]$. Alphabetic characters may be upper or lower case. The string
`Print Level = 1`
is an example of a string used to set an optional parameter. For each option the string contains one or more of the following items:
 – a mandatory keyword; – a phrase that qualifies the keyword; – a number that specifies an Integer or double value. Such numbers may be up to $40$ contiguous characters which can be read using C's d or g formats, terminated by a space if this is not the last item on the line.
Blank strings and comments are ignored. A comment begins with an asterisk (*) and all subsequent characters in the string are regarded as part of the comment.
The file containing the options must start with Begin and must finish with End. An example of a valid options file is:
```Begin * Example options file
Print level = 5
End```
Optional parameter settings are preserved following a call to nag_opt_nlp_revcomm (e04ufc) and so the keyword ${\mathbf{Defaults}}$ is provided to allow you to reset all the optional parameters to their default values before a subsequent call to nag_opt_nlp_revcomm (e04ufc).
A complete list of optional parameters, their abbreviations, synonyms and default values is given in Section 12 in nag_opt_nlp_revcomm (e04ufc).

None.

## 5Arguments

1:    $\mathbf{fileid}$Nag_FileIDInput
On entry: the ID of the option file to be read as returned by a call to nag_open_file (x04acc).
2:    $\mathbf{lwsav}\left[120\right]$Nag_BooleanCommunication Array
3:    $\mathbf{iwsav}\left[610\right]$IntegerCommunication Array
4:    $\mathbf{rwsav}\left[475\right]$doubleCommunication Array
The arrays lwsav, iwsav and rwsav MUST NOT be altered between calls to any of the functions nag_opt_nlp_revcomm_option_set_file (e04udc), nag_opt_nlp_revcomm_option_set_string (e04uec), nag_opt_nlp_revcomm (e04ufc) or nag_opt_nlp_revcomm_init (e04wbc).
5:    $\mathbf{fail}$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_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
One or more lines of the options file is invalid.
NE_MISSING_BEGIN
End-of-file was found before Begin was found.
NE_MISSING_END
Begin was found, but end-of-file was found before End was found.
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.
Could not open options file with ${\mathbf{fileid}}=〈\mathit{\text{value}}〉$.

Not applicable.

## 8Parallelism and Performance

nag_opt_nlp_revcomm_option_set_file (e04udc) is not threaded in any implementation.

nag_opt_nlp_revcomm_option_set_string (e04uec) may also be used to supply optional parameters to nag_opt_nlp_revcomm (e04ufc).

## 10Example

This example solves the same problem as the example for nag_opt_nlp_revcomm (e04ufc), but in addition illustrates the use of nag_opt_nlp_revcomm_option_set_file (e04udc) and nag_opt_nlp_revcomm_option_set_string (e04uec) to set optional parameters for nag_opt_nlp_revcomm (e04ufc).

### 10.1Program Text

Program Text (e04udce.c)

### 10.2Program Data

Program Options (e04udce.opt)

Program Data (e04udce.d)

### 10.3Program Results

Program Results (e04udce.r)