sds_id	IN:	Data set identifier returned by SDcreate or SDselect
	cal	OUT:	Calibration factor
	cal_err	OUT:	Calibration error
	offset	OUT:	Uncalibrated offset
	offset_err	OUT:	Uncalibrated offset error
	data_type	OUT:	Data type of uncalibrated data

	Purpose	Retrieves the calibration information associated with a data set.
	Return value	Returns SUCCEED (or 0) if successful and FAIL (or -1) otherwise.
	Description	SDgetcal reads the calibration record attached to the data set identified by the parameter sds_id. A calibration record is comprised of four 64-bit floating point values followed by a 32-bit integer. The information is listed in the following table:

cal	calibration factor
cal_err	calibration error
offset	uncalibrated offset
offset_err	uncalibrated offset error
data_type	data type of the uncalibrated data

		The relationship between a calibrated value cal_value and the original value orig_value is defined as orig_value = cal * (cal_value - offset).
		The variable offset_err contains a potential error of offset, and cal_err contains a potential error of cal. Currently the calibration record is provided for information only. The SD interface performs no operations on the data based on the calibration tag.

	FORTRAN	integer function sfgcal(sds_id, cal, cal_err, offset, offset_err, data_type)
		integer sds_id, data_type
		real*8 cal, cal_err, offset, offset_err