SUPACK2 - pack segy trace data into 2 byte shorts

supack2 <segy_file >packed_file gpow=0.5

Required parameters:
none

Optional parameter:
gpow=0.5 exponent used to compress the dynamic
range of the traces


Credits:
CWP: Jack K. Cohen, Shuki Ronen, Brian Sumner

Revised: 7/4/95 Stewart A. Levin Mobil
Changed encoding to ensure 2 byte length (short is
8 bytes on Cray).

Caveats:
This program is for single site use. Use segywrite to make
a portable tape.

We are storing the local header words, ungpow and unscale,
required by suunpack2 as floats.

Notes:
ungpow and unscale are defined in segy.h
trid = SHORTPACK is defined in su.h and segy.h

Trace header fields accessed: ns
Trace header fields modified: ungpow, unscale, trid