sushw

seismic software,very useful

SUSHW - set header word using trace number, mod and integer divide
sushw <stdin >stdout key=cdp a=0 b=0 c=0 d=0 j=1
Required parameters:
	none (no op)
Optional parameters:
	key=cdp		header key word to set
	a=0		value on first trace
	b=0		increment within group
	c=0		group increment
	d=0		trace number shift
	j=ULONG_MAX	number of elements in group
NOTES:
The value of header word key is computed using the formula:
	i = itr + d
	val(key) = a + b * (i % j) + c * (i / j)
where itr is the trace number (first trace has itr=0, NOT 1)
 Example:
 	sushw <indata key=dt a=4000 |
 	sushw key=sx a=6400 c=-100 j=32 |
 	sushw key=offset a=200 b=200 j=32 |
 	suchw key1=gx key2=offset key3=sx b=1 c=1 |
 	suchw key1=cdp key2=gx key3=sx b=1 c=1 d=2 >outdata
In this example, we set every dt field to 4ms.  Then we set the first
32 shotpoint fields to 6400, the second 32 shotpoint fields to 6300 and
so forth.  Next we set each group of 32 offset fields to 200, 400, ...,
6400.  Finally we use suchw to set the receiver point and cdp fields
using the sx and offset fields (we choose to use the actual location
for the cdp fields instead of the conventional 1, 2, 3, ...
enumeration).