Finishing the location of hypocentre:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Input:
  TREF...     Optional reference arrival time.  Need not be specified.
  $2,$3,$4... Temporary files to accumulate intermediate results.
Output:
  $5...       Grid values of the relative probability.
  $6...       Grid values of the mean hypocentral time.
  $7...       Grid values of the standard deviation of hypocentral time.
For example refer to
wb2-loc.h.

A=1./$2
THYPO=$3/$2
SIGMA=$4*$4
SIGMA=-0.5*SIGMA
$5=EXP(SIGMA)
$6=THYPO+TREF
$7=SQRT(A)