Synopsis
		sfmake_ix_indx < infile.rsf > out.rsf verbose=1 ilinemin=-1e31 ilinemax=-1e31 xlinemin=-1e31 xlinemax=-1e31 ilineinc=10 input= headers= iline= xline= indxdir=

These indexes are intended to be used by future sftahsort and sftah5dinterp.

EXAMPLE:
Runnning the programs:

sfmake_ix_indx \
verbose=1 \
input=npr3_fielda.rsf \
indxdir=npr3_field \
ilineinc=10 \
iline=iline \
xline=xline \
append=no \
>/dev/null
sfmake_ix_indx \
verbose=1 \
input=npr3_fieldb.rsf \
indxdir=npr3_field \
ilineinc=10 \
iline=iline \
xline=xline \
append=yes \
>/dev/null

Will create a set of files:
npr3_field/il0
npr3_field/il5
...
npr3_field/il350
and
npr3_field/filename_indx

The file npr3_field/il15 will contain the trace headers of the traces with
trace header "iline" nearest to 15. The file also has the file number and
the trace number, so you can locate the trace in the input files (either
npr3_fielda.rsf or npr3_fieldb.rsf. The trace headers in the file are all
sorted by xline. With this information you can quickly find all the traces
that are in a range of ilines and xlines. This supports sftah5dinterp which
processes all the traces in a midpoint superbin that might be 800 meters by 800
meters (about 16 ilines and 32 xlines). This is not a simple sort problem
because sftah5dinterp processes data in overlapping bin (i.e. the 800 meter
superbin centers moveup by 400 meters). Overlapping superbins are supported by
allowing traces to be reread.

The program also allows sftahsort to read from multiple files. This is useful
on larger 3D projects where the input data is on multiple segy files.
Previously I merged the files into one big file after running sfsegyread. This
required an additional copy of all the data to be saved on disk.

Parameters
		string headers= Trace header file name. Default is the input data file name, with the final .rsf changed to _hdr.rsf   string iline= header key for the main index key. This should be iline, but you may have non-standard trace headers or a wierd use of this program   int ilineinc=10 incrment in iline for the index   float ilinemax=-1e31 maximum "iline" header key to include in the index. Use this parameter to remove null trace headers or traces outside project area.   float ilinemin=-1e31 minimum "iline" header key to include in the index. Use this parameter to remove null trace headers or traces outside project area.   string indxdir= The name of the directory containing the iline,xline index. This directory will be in DATAPATH (probably the environment variable). The directory also continues a file "filenames", a list of the trace and header files that contributes to this index. The directory contains files with names "indx#" here # is an integer multiple of ilineinc. These files contains a record for each contributing trace with filenumber, tracenumber, and the trace header. The file containing the trace is determined using the can be read by using the filenumber and the "filenames" file. The tracenumber defines the location of the trace in the file.   string input= Input file for traces amplitudes   int verbose=1 flag to control amount of print 0 terse, 1 informative, 2 chatty, 3 debug   string xline=   float xlinemax=-1e31 maximum "xline" header key to include in the index. Use this parameter to remove null trace headers or traces outside project area.   float xlinemin=-1e31 minimum "xline" header key to include in the index. Use this parameter to remove null trace headers or traces outside project area.