
UPDATES:

 4/20/92  The linear system solver (FACTOR/BACSUB) used by
          SCOOTER was not initializing one of the variables
          to 0.  Causing sporadic NaN/Infinity problems when
          using IEEE arithmetic.  A similar problem occured
          with the axis length specification for plots in
          FIELDS.

 9/25/92  The option of putting an acousto-elastic halfspace
          on the top was not working properly. (It took the
          density from the lower halfspace.)

10/28/92  FIELDS produced erroneous results when the
          number of wavenumber points exceeded the
          dimension limit of 10000.  A test has been
          added to flag this error and the dimension
          has been increased to 50000.

12/ 7/92  SPARC modified so that if the parameters are
          such that the time integration is fully explicit
          (ALPHA=BETA=0.0) then the linear solver is
          bypassed.  This gives some improvement in
          performance.

 1/18/93  FIELDS was writing an extra vector at zero range
          in cases where subsampling was required.  This caused
          PLOTSLICE to have problems plotting TL.

 2/17/93  Error in PLOTTS fixed.  The FLOW and FHIGH numbers were
          always used for bandpass filtering even when the
          option 'N' (no filtering) was selected.  If the
          bandpass filter were wider than the signal bandwidth
          you effectively disabled filtering.  If, however,
          you had a narrow bandpass filter then it was always
          applied to the signal and might have produced confusing
          results.

 3/16/93  Error in SOURCE fixed.  When the time-reversal
          option was used, SOURCE reversed the time coordinates
          as many times as there were sources.  As a result,
          the time series was reversed but the times associated
          with the data were not.

 6/10/93  Error in FIELDS fixed. Occasionally it would
          reference an array index that was one point
          beyond the last calculated value. This had
          no significant effect on the TL field but
          caused a floating point exception on machines
          that trap references to an undefined value.

          Error in SCOOTER fixed. SCOOTER was extracting
          the density at the source incorrectly: it took
          a density at a nearby point. When the nearby
          point was outside the grid, an undefined
          density was returned.

12/29/93  FIELDS modified so that the specified ranges of
          receivers are not changed.

 3/17/95  The plot option in FIELDS has been removed to make
          SCOOTER structurally similar to KRAKEN. Similarly,
          the input file to fields should now be called fields.flp
          rather than fields.plp.

 6/10/95  In SPARC the option for producing a time-series on a
          horizontal array was not working properly. The array
          a variable RTSTRR was being loaded instead of RTSRR.

 1/98 FIELDS automatically increases the minimum range, RMIN, to
      ensure that we don't try to calculate a field value right on
      the source. Previously RMIN was bumped to 1 m which caused
      problems for ultrasonic applications. Now it is bumped
      to RMAX / 100000. 
