AXUNITS - Sets a new units value for an axis within an NDF data structure

Description:

This routine sets a new value for a UNITS component of an existing NDF  AXIS  data structure. The NDF is accessed in update mode and any pre-existing UNITS component is over-written with a new value. Alternatively, if a `null' value (!) is given for the UNITS parameter, then the NDF's axis UNITS component will be erased. If an AXIS structure does not exist, a new one whose centres are pixel co-ordinates is created.

Usage:

axunits ndf units dim

Parameters:

DIM = _INTEGER (Read)

The axis dimension for which the units is to be modified. There are separate units for each NDF dimension. The value must lie between 1 and the number of dimensions of the NDF. This defaults to 1 for a one-dimensional NDF. The suggested default is the current value. []

NDF = NDF (Read and Write)

The NDF data structure in which an axis UNITS component is to be modified.

UNITS = LITERAL (Read)

The value to be assigned to the NDF's axis UNITS component (e.g. "Pixels" or "km/s"). UNITS describes the physical units of the quantity measured along the axis. This value may later be used by other applications for labelling graphs and other forms of display where the NDF's axis co-ordinates  are shown. The suggested default is the current value.

Examples:

axunits ngc253 "arcsec" 2

Sets the UNITS component of the second axis dimension of the NDF structure ngc253 to have the value "arcsec".

axunits ndf=spect units=Angstrom

Sets the axis UNITS component of the one-dimensional NDF structure spect to have the value "Angstrom".

axunits datafile units=! dim=3

By specifying a null value (!), this example erases any previous value of the UNITS component for the third dimension in the NDF structure datafile.

Related Applications :

KAPPA: AXLABEL, SETAXIS, SETUNITS.