NAME

     fdslice - retrieve requested data slices from or transpose a
     complete dataset.

SYNOPSIS

     fdslice  [  -Nntap  ]  [  -Ootap  ]  [  -ss[start_sample]  |
     -s[start_time]  ]  [  -es[end_sample]  |  -e[end_time]  ]  [
     -is[increment_in_samples] | -i[increment_time] ]  [  -V ]  [
     -? ]

DESCRIPTION

     fdslice is designed to retrieve a slice (or slices) of  data
     from  a USP data set. It is a faster variation of dslice and
     has the added capability of utilizing piped input  and  out-
     put. The program was designed to work optimally for multiple
     slices on large data sets. The output consists of one record
     for  each requested slice and each output record has a trace
     count equal to the number of records on the  input  dataset.
     However,  the  traces  are  output  in an order by which the
     first trace for each slice is output, then the second trace,
     etc.  Each  trace has a trace length in samples equal to the
     number of traces/record  of  the  input.  The  data  may  be
     resorted  back  into  record  order  via  resorter  with the
     -fdslice option; this is illustrated in the EXAMPLES section
     below.  A newer program called qdslice has been developed to
     perform the same functions in proper record/trace order when
     dealing  with disk output. By dealing with disk alone and by
     utilizing a buffered output area, even greater speeds may be
     obtained.

     Input consists of specifications  of  the  location  of  the
     first slice, last slice, and intermediate incremental slices
     to take, if any. This may be specified  either  in  time  or
     samples.  If  specified in time, the units are assumed to be
     the same as that used by the sample  interval  in  the  line
     header.  (ie. if the sample interval is in milliseconds, the
     specified times are assumed to be in milliseconds).  Command
     line  arguments  are further detailed in the OPTIONS section
     below.

     If the user wishes to order the slices in another direction,
     the program transp, which transposes data, may be used.

  Command line arguments
     -ss start_sample
          Location  by  sample  number  of  the  first  slice  to
          extract.

     -es end_sample
          Location by sample number of the last slice to extract.
          Default is the last sample.

     -is increment_in_samples
          Increment in samples between subsequent slices.

     -s start_time
          Time of the first slice to extract. (  Specified  times
          are relative to the sample interval units. )

     -e end_time
          Time of the last slice to extract.

     -i increment_time
          Time to increment between subsequent slices.

     -V   Enter the command line argument '-V' to get  additional
          printout.

     -?   Enter the command line  argument  '-?'  to  get  online
          help.   The program terminates after the help screen is
          printed.

EXAMPLES

     First we grab the trace headers  from  the  input  data  and
     store  them  away since we'll need them at the end of all of
     this:

     step 1: editt -Nslice.in -e8 -Ohdrs

     where we put an end time of some value just greater than the
     sample  interval  to get at least one sample in each trace +
     of course the header itself.

     Let's take a slice every 8 ms. from 1200 ms. to 1300 ms. and
     then  sorts it into order with each output record represent-
     ing a single slice of the data.

     step 2: fdslice -Nslice.in -s1200 -e1300 -i8 |
     step 2: resorter -Oslice.out -fdslice

     After processing the time slices to get back to the original
     data order run the following steps:

     step 3: fdslice -Nslice.proc -ss1 -is1 |
     step 3: resorter -Oslice.inter -fdalise
     step 4: fdslice -Nslice.inter -ss1 -is1 |
     step 4: resorter -Ofinal.data -fdslice

     The data will now be in  the  original  order  but  will  be
     without  sensible trace headers. We can  now make use of the
     header file we created in the first step:

     step 5: hdrswap -N1final.data -N2hdrs | utop -Ofinal.dataout
     -dt4
     where we grab the trace headers from the original pre-sliced
     input  data.  We also have to specifically put in the sample
     interval back in the line header. We've now sliced and diced
     our 3D volume.

     For more information on the sorting routines, refer to their
     respective USP manual pages.

AUTHOR(S)

     joe m. wade

SEE ALSO

     qdslice(1),dslice(1),transp(1),resorter(1)

COPYRIGHT

     copyright 2001, Amoco Production Company
               All Rights Reserved
          an affiliate of BP America Inc.