SETTYPE - Sets a new numeric type for the DATA and VARIANCE components of an NDF

Description:

This application allows the numeric type  of the DATA and VARIANCE components of an NDF  to be changed. The NDF is accessed in update mode and the values stored in these components are converted in situ to the new type. No other attributes of the NDF are changed.

Usage:

settype ndf type

Parameters:

COMPLEX = _LOGICAL (Read)

If a TRUE value is given for this parameter, then the NDF's array components will be altered so that they hold complex values, an imaginary part containing zeros being created if necessary. If a FALSE value is given, then the components will be altered so that they hold non-complex values, any imaginary part being deleted if necessary. If a null (!) value is supplied, the value used is chosen so that no change is made to the current state. [!]

DATA = _LOGICAL (Read)

If a TRUE value is given for this parameter, then the numeric type of the NDF's data array will be changed. Otherwise, this component's type will remain unchanged. [TRUE]

NDF = NDF (Read and Write)

The NDF data structure whose array components are to have their numeric type changed.

TYPE = LITERAL (Read)

The new numeric type to which the NDF's array components are to be converted. The value given should be one of the following: _DOUBLE, _REAL, _INTEGER, _WORD, _UWORD, _BYTE or _UBYTE (note the leading underscore). Existing pixel values stored in the NDF will not be lost, but will be converted to the new type. Any values which cannot be represented using the new type will be replaced with the bad-pixel  value.

VARIANCE = _LOGICAL (Read)

If a TRUE value is given for this parameter, then the numeric type of the NDF's VARIANCE  array will be changed. Otherwise, this component's type will remain unchanged. [TRUE]

Examples:

settype rawdata _real

Converts the data and variance values held in the NDF data structure rawdata to have a numeric type of _REAL (i.e. to be stored as single-precision floating-point numbers).

settype inst.run1 _word novariance

Converts the data array in the NDF structure inst.run1 to be stored as word (i.e. Fortran INTEGER$*$ 2) values. No change is made to the VARIANCE component.

settype hd26571 _double complex

Causes the DATA and VARIANCE components of the NDF structure hd26571 to be altered so as to hold complex values using double precision numbers. The existing pixel values are converted to this new type.

Timing :

The execution time is approximately proportional to the number of pixel values to be converted.

Related Applications :

FIGARO: RETYPE.