### NDF_TUNE

Set an NDF_ system tuning parameter

#### Description:

The routine sets a new value for an NDF_ system internal tuning parameter.

#### Invocation

CALL NDF_TUNE( VALUE, TPAR, STATUS )

#### Arguments

##### VALUE = INTEGER (Given)
New value for the tuning parameter.
##### TPAR = CHARACTER $\ast$ ( $\ast$ ) (Given)
Name of the parameter to be set (case insensitive). This name may be abbreviated, to no less than 3 characters.
##### STATUS = INTEGER (Given and Returned)
The global status.

#### Notes:

The following tuning parameters are currently available:
• ’AUTO_HISTORY’; Controls whether to include an empty History component in NDFs created using NDF_NEW or NDF_CREAT. If the tuning parameter is zet to zero (the default), no History component will be included in the new NDFs. If the tuning parameter is zet non-zero, a History component will be added automatically to the new NDFs.

• ’DOCVT’: Controls whether to convert foreign format data files to and from native NDF format for access (using the facilities described in SSN/20). If DOCVT is set to 1 (the default), and the other necessary steps described in SSN/20 have been taken, then such conversions will be performed whenever they are necessary to gain access to data stored in a foreign format. If DOCVT is set to 0, no such conversions will be attempted and all data will be accessed in native NDF format only. The value of DOCVT may be changed at any time. It is the value current when a dataset is first accessed by the NDF_ library which is significant.

• ’KEEP’: Controls whether to retain a native format NDF copy of any foreign format data files which are accessed by the NDF_ library (and automatically converted using the facilities described in SSN/20). If KEEP is set to 0 (the default), then the results of converting foreign format data files will be stored in scratch filespace and deleted when no longer required. If KEEP is set to 1, the results of the conversion will instead be stored in permanent NDF data files in the default directory (such files will have the same name as the foreign file from which they are derived and a file type of ’.sdf’). Setting KEEP to 1 may be useful if the same datasets are to be re-used, as it avoids having to convert them on each occasion. The value of KEEP may be changed at any time. It is the value current when a foreign format file is first accessed by the NDF_ library which is significant.

• ’ROUND’: Specifies the way in which floating-point values should be converted to integer during automatic type conversion. If ROUND is set to 1, then floating-point values are rounded to the nearest integer value. If ROUND is set to 0 (the default), floating-point values are truncated towards zero.

• ’SHCVT’: Controls whether diagnostic information is displayed to show the actions being taken to convert to and from foreign data formats (using the facilities described in SSN/20). If SHCVT is set to 1, then this information is displayed to assist in debugging external format conversion software whenever a foreign format file is accessed. If SHCVT is set to 0 (the default), this information does not appear and format conversion proceeds silently unless an error occurs.

• ’TRACE’: Controls the reporting of additional error messages which may occasionally be useful for diagnosing internal problems within the NDF_ library. If TRACE is set to 1, then any error occurring within the NDF_ system will be accompanied by error messages indicating which internal routines have exited prematurely as a result. If TRACE is set to 0 (the default), this internal diagnostic information will not appear and only standard error messages will be produced.

• ’WARN’: Controls the issuing of warning messages when certain non-fatal errors in the structure of NDF data objects are detected. If WARN is set to 1 (the default), then a warning message is issued. If WARN is set to 0, then no message is issued. In both cases normal execution continues and no STATUS value is set.

• ’PXT...’: Controls whether a named NDF extension should be propagated by default when NDF_PROP or NDF_SCOPY is called. The name of the extension should be appended to the string "PXT" to form the complete tuning parameter name. Thus the tuning parameter PXTFITS would control whether the FITS extension is propagated by default. If the value for the parameter is non-zero, then the extension will be propagated by default. If the value for the parameter is zero, then the extension will not be propagated by default. The default established by this tuning parameter can be over-ridden by specifying the extension explicitly within the CLIST argument when calling NDF_PROP or NDF_SCOPY. The default value for all "PXT..." tuning parameters is 1, meaning that all extensions are propagated by default.