This IDL procedure will create a Starlink HDS file corresponding to the IDL variable, which may be a scalar, array or structure.

IDL_struct

filename

• Type correspondence is as follows:

  floating –$>$ _REAL

  double-precision –$>$ _DOUBLE

  byte –$>$ _UBYTE (unless _LOGICAL, see below).

  integer –$>$ _WORD (unless _LOGICAL, see below).

  longword integer –$>$ _INTEGER (unless _LOGICAL, see below).

  string –$>$ _CHAR*(IDL string size)

• Each HDS structure will have a type as defined by the HDSSTRUCTYPE component of the IDL structure. If there is no such component, the HDS type is blank.

• Byte, integer or longword integer components which have LOGICAL_ prefixed to their name will be converted to _LOGICAL HDS components and the prefix will be removed from the name.
• IDL strings will be converted into HDS _CHAR components whose size is the size of the IDL string. If a size greater than the used length is required, the IDL string must be padded with blanks.
• HDS arrays of structures will be created from IDL structures having the form produced from HDS arrays of structures by HDS2IDL.

IDL> idl2hds, data_struct, ’my_file’

Assuming data_struct is an IDL structure, this creates the HDS file ’my_file.sdf’ with a corresponding structure.

• It is not possible to obtain an identical structure in all cases (see "Notes").
• It is not possible to produce HDS components of type _UWORD or _BYTE.
• Complex values are not handled.
• IDL arrays of more than 1 structure are not handled.
• Only a complete HDS file can be written.

Convert: HDS2IDL.