15.08.03:
      The program gaspan has been critically overviewed. The
      fit procedure has been redesigned  and some sources of
      crashes have been removed. Quite some changes in the
      commands and options have been incorporated:

      1. Tektronix graphics is no longer supported.

      2. The format of the output for the peak areas has been adapted to
         the size of the error of the peak area: Only two digits of the 
         error will be seen.
        
      3. The output file of the "set fit -print" command has been changed
         from "lptgaspan" to "fithistory.gsp"

      4. The history mechanisme for the keyboard input has been
         extended over different sessions (assuming the sessions are
         in the same working directory)

      5. changed commands:

         a) the command "limitations" has been changes to "show limitations"

         b) The degree of the background polynomial can be added to the
            "fit" - command as further optional parameter

         c) The command "save parameters" has been absorbed into the
            command "save options"

         d) the command "show sample" has been added. It is to be
            used togather with the command "set parameter -check"

         e) The command "test printout" has been partially made
            available to the user. Use "help test printout" to
            get more information.

      6. changed and added options:

         a) in "set display":

            i) the options "-centroid", "-gauss-position" and
               "-tail_include" have been added. They control the
               position of the peak markers.

           ii) the option "-saveall=filename" (and "-nosaveall")
               has been added. It allows to put all displays into
               one postscript file.

          iii) gaspan will normally only display the final fit.
               Intermediate steps are shown when seting th option
               "-intermediate"

           iv) the option "-out" has been changed to "-print"

        b) the argument of the option "set fit -out" is obsolete:
           file names are derived from the data filename.

        c) in "set peak"

            i) the option "-include_background_tail" has been added.

           ii) "-energy": The energy calibration allows to include
               negativ powers in the channel number. The best polynomial
               is searched for if no degree is defined.

        d) The option "set statistics -smooth_errors" has been added.

        e) A step function can now be added to the fit function
           with the command "set tail -step"

        f) The commands "set parameter -extended_check" and 
           "set parameter -full_check" and "set parameter -all_check"
           have been addeD TO "set parameter -check" to allow for
           different stages of fit parameter checking. The user
           can view the quality of the parameters by using the
           commands "test printout 7" and "show sample"

31.05.00:   1. gaspan can now be compiled with Xwindow graphics
               instead of tektronix graphics:
                     make xgaspan
               Note: remapping and resizing of the graphics window
                     does not work properly in this version.
           
            2. A new spectrum format has been implemented: .daterr
               with this ascii format it is possible to specify
               explicitly the error of the channel contents.
               see "help set format"
           
            3. Whereas channel numbers are still assumed to be integer
               numbers, the display will now  be able to handle channel
               contents with fractional numbers.
           
            4. The output of the results will also be able to handle peak
               areas smaller than 1.
           
            5. new commands:
                 a) set display -errorbar
                    set display -histogram
           
                 b) the command "show spectrum" will browse through the
                    spectrum if it is longer than 4096 channels
           
                 c) the command "show spectrum" might be used with  optional
                    arguments minchannel, maxchannel
                    the region defined by set fit -region=.... will not be
                    changed by these arguments.
                 d) the commands "go" and "fit" have been seperated by their
                    function. 
                    "go" works still as in previous versions.
                    "fit [minchannel,maxchannel]" assumes only one fit region
                     which can be specified in the optional arguments. This
                     fit region must comply with the restriction of one
                     fit region: the region must be less than 1500 channels
                     and should not contain more than 27 peaks.
                     The options "set fit -interactive" and "set fit -save"
                     are activated during command execution and the fit
                     procedure is finished by executing the command
                     "show fit"
            6. the command "set fit -[no]priority" has been removed

            7. All floating point variables have been changed to double
               precision. This improved the reliability - especially
               with tail ftting - considerably.

14.07.98: changes to spectrum size of maximum of 999999 channels,
          introduction to .fft format
10.04.98: file gaspan.f: outputformat for tail parameter in gaspas changed
                          to accomodate larger values for the decay constant
21.01.98: file gasfun.f: there was a not legal cutoff in the error function
                         which has been removed, appeared as a break in strong
                         tails
          file gaspan.f: due to the repair in gasfun.f it was necessary to
                         restrict the range of the width variation to
                         values smaller than 0.8. This restriction applies
                         automatically if tails are requested, however the 
                         rangeof the width variation can be encreased afterwards
04.12.97: file readdat.c: changed to unlimited spectrum size. note that
                          the spectrum size is still restricted by other
                          routines to 99999 channels
          file gaspea.icl: TOTALPEAKS increased from 400 auf 1000,
                           MAXREGIONS increased from 50 to 100
11.11.97: file gaspan.f: there was an error in the option set back -fixed
21.10.97: file gaseic.f: The algorithmus of fitting efficiency calibrations 
                         has been improved 
19.06.97: adaption to IRIX 6.2
