Name

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SXGPAR

Purpose

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Obtain group parameter value in SDAS/FITS file

Calling Sequence

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result = sxgpar( h, par, name, [ type, sbyte, nbytes] )

Inputs

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h - header returned by SXOPEN
par - parameter block returned by SXREAD or multiple
parameter blocks stored in array of dimension
greater than one.
name - parameter name (keyword PTYPEn) or integer
parameter number.

Optional Input/output

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type - data type (if not supplied or null string, the
header is searched for type,sbyte, and nbytes)
sbyte - starting byte in parameter block for data
nbytes - number of bytes in parameter block for data

Output

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parameter value or value(s) returned as function value

Side Effects

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If an error occured then !err is set to -1

Operational Notes

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Supplying type, sbyte and nbytes greatly decreases execution
time. The best way to get the types is on the first call
pass undefined variables for the three parameters or set
type = ''. The routine will then return their values for
use in subsequent calls.

Method

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The parameter type for parameter n is obtained
from PDTYPEn keyword. If not found then DATATYPE keyword
value is used. If that is not found then BITPIX is
used. BITPIX=8, byte; BITPIX=16 integer*2; BITPIX=32
integer*4.

History

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version 1 D. Lindler Oct. 86
version 2 D. Lindler Jan. 90 added ability to process
multiple parameter blocks in single call
version 3 D. Lindler (converted to New vaxidl)
      Apr 14 1991 JKF/ACC - fixed make_array datatypes(float/double)
Converted to IDL V5.0 W. Landsman September 1997