NAME

     ttothen - apply t-to-the-n gain or exponential gain curve or
     V**2 - t scaling or angle based offset gain

SYNOPSIS

     ttothen [ -Nntap ] [ -Ootap ] [ -vvtap  ]  [  -V0vinit  ]  [
     -iordiord  ]  [  -root  ]  [  -nsns ] [ -nene ] [ -rsirs ] [
     -reire ] [ -aalpha ] [ -exppower ] [ -A ] [ -NMOAP ] [ -E  ]
     [ -I ] [ -V ] [ -? ]

DESCRIPTION

     ttothen applies a deterministic gain curve to the data

     ttothen gets both its data and its parameters  from  command
     line  arguments.  These arguments specify the input, output,
     the multiplicative factor and the exponent.  The gain  curve
     is  derived  according  to several options: (1) simple power
     function (T **n);  (2)  zero  offset  V**2-t  function;  (3)
     offset dependent angle-driven functiom.

  Command line arguments
     -Nntap
          Enter the input data set name or file immediately after
          typing  -N;  entering  nothing  specifies a stdin pipe.
          This input put file should include  the  complete  path
          name  if  the  file  resides  in a different directory.
          Example -N/b/vsp/dummy tells the program  to  look  for
          file 'dummy' in directory 'vsp' stored on the 'b' disk.

     -Ootap
          Enter the output data  set  name  or  file  immediately
          after typing -O.  This output file is not required when
          piping the output to another process.  The output  data
          set also requires the full path name (see above).

     -vvtap
          For V**2 - T  or offset dependent  scaling,  enter  the
          velocity data set name or file immediately after typing
          -v; entering nothing specifies  simple  power  function
          gain  curve.  If  used this must be a velocity tape. It
          can either have a single trace or have as  many  traces
          as  there  are  traces  of  input data. If the velocity
          traces run out before the end of input is reached  then
          the  last  velocity  trace is repeated. If the velocity
          trace is shorter than the input traces  then  the  last
          velocity  is repeated. The record & trace selects below
          will NOT be applied to the velocity data set.

     -iordiord
          Enter smoothing order  to  apply  to  velocity  traces.
          Dwfault = no smoothing

     -V0vinit
          For (V**2)/V0 - T scaling, enter the  initial  velocity
          immediately after typing -V0.  Default = 1.0

     -root
          Enter the command line  argument  '-root'  to  use  the
          square  root  of  the  V-squared-t  scaling above. This
          simulates cylindrical spreading rather  than  spherical
          spreading.

     -A   Enter the command line argument '-A' to use the  offset
          dependent  scaling option. This is based on the work of
          Newman (Geophysics, 1978). Angles are computed  from  a
          layer  cake  model  derived from the velocity trace and
          these are used in the gain calculation. The angle  com-
          putations here are the same as in program angst.

     -rs irs
          (integer) First record to process (default = 1)

     -re ire
          (integer) Last record to process (default = all)

     -ns ns
          First trace in record to process (default = 1)

     -ne ne
          Last trace in record to process (default = all)

     -aalpha
          Enter the multiplicative scale  factor.   This  is  the
          value  that  the  gain  curve  will have at one second.
          Default = 1.0

     -exppower
          For  the  simple  power  function  option:  enter   the
          exponent  of  the  gain  curve power function ( time **
          power).  Default = 2.0 if no vtap specified, 1 if  vtap
          specified.

     -E   For the simple power function option: enter the command
          line  argument '-E' to apply the exponential gain curve
          alpha*exp(power*t); otherwise the gain curve is typical
          t-to-the-n: alpha*t**power

     -I   Enter the command  line  argument  '-I'  to  apply  the
          inverse of the gain curve

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


     -?   Enter this (or '-?' if you are running in  c-shell)  to
          get  online  help.   The  program  will terminate after
          printing this.

EXAMPLES

     ttothen -Nindata -Oodata

     where a simple power function is assumed.

     ttothen -Nindata -Oodata -vvel_data -root

     where a zero offset cylindrical spreading function  will  be
     applied.

     bdnmo -Nindata -vvel_data | ttothen -vvel_data  -A  |  bdnmo
     -Oodata -vvel_data -R

     where we apply a full offset dependent  spreading  function.
     We first apply nmo and the unapply it after gain correction.

COPYRIGHT

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