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)