Delila Program: log

log program

Documentation for the log program is below, with links to related programs in the "see also" section.

{version = 1.02; (* of log.p 2002 Oct 25}

(* begin module describe.log *)
(*
name
   log: compute log of a data column

synopsis
   log(histog: in, logp: in, xyin: out, output: out)

files

   histog:  a histogram file from genhis.
      First column: position
      Second column: value

   xyin:  output file for xyplo.  The second column is used to compute
      the log, base 2.
      Negative or zero values are set to a very large negative number.

      First column: position
      Second column: log2(value)
      Third column: value

      This substitutes the log for the value, but keeps
      the original value around for inspection.

   logp:  parameters to control the program.  The file must contain the
      following parameters, one per line:

      parameterversion: The version number of the program.  This allows the
         user to be warned if an old parameter file is used.

      not used, could be used to set base of log.

   output: messages to the user

description

   Compute the base 2 log of the second data column of a histog file
   from the genhis program.  This allows the double log to be
   plotted using xyplop's log feature.  On a double log plot, a
   Gaussian distribution should show up as a slope of exactly -2.

examples

documentation

see also

   source of histog file: genhis.p

   program to plot the result: xyplo.p

author

   Thomas Dana Schneider

bugs

   Only the second column is computed.
   The parameter file could be used to set the base.

technical notes

*)
(* end module describe.log *)
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