function astats
%           Gives information obout the stats used in arpro.
%                Uses the helpfun.m matlab function.
%
%                      Mike Sparrow Jan. '97
%
titleStr = ['About the Statistics'] ;
helpStr1 = ['Following Krauss and Boning (1987), the error in    '
            'the Eulerian velocity can be calculated from :      '
            '                          ____                      '
            '                 2*sqrt(u`^2)                       '
            '         dU = -----------------                     '
            '                   sqrt(Nm)                         '
            '                ___                                 '
            'where sqrt(u`^2) is the standard deviation of Umean '
            'and Nm are the statistically independent data.      '
            'If we have N  observations, and T is the lagrangian '
            'time scale, then :                                  '
            '                                                    '
            '                  N                                 '
            '         Nm = ---                                   '
            '                  T                                 '
            '                                                    '
            'If an estimate of T has not been made in a certain  '
            'grid box (either by autocorrelation or by stream    '
            'function) then ARPRO sets T11 (meridional component)'
            'and T22 (the zonal component) equal to 1.           '             
            '                                                    '
            'Vectors are drawn from the centre of each box (use  '
            'the "Grid" option to see the boxes) representing the'
            'mean eulerian velocity in each box. The results are '
            'written to the file "errorbar.asc which should be   '
            'examined if more detail (including U* and dU*) is   '
            'required (U* is the root of the mean square of dU). '
            'Note - if rows or cols =1 then the values are       '
            'written out on screen rather than plotted...        '
            '                                                    '
            'As well as the above, estimates of K (the eddy      '
            'diffusivity) and L (the integral time scale) as well'
            'as their associated errors are produced.            '
            '                                                    '
            '*The best method to obtain good statistical results '
            '*is to choose the area and floats required, then    '
            '*"T by autocorrelation" and then run "Errors".      '
            '                                                    '
            'The button "specifyT" has been added to allow the   '
            'user to force T11 and T22 to specific values. This  '
            'can be useful if, for example, you wish to find the '
            'error of the velocities of one float but using a    '
            'a previously calculated value of T.                 '
            '                                                    '
            'Two good references for the statistics are :        '
            '                                                    '
            '"Lagrangian properties of eddy fields in the        '
            'northern North Atlantic as deduced from satellite   '
            'tracked bouys", W.Krauss and C.W.Boning, Journal of '
            'Marine Research, 45, 259-291, 1987.                 '
            '                                                    '
            '"Advection and eddy mixing in the Mediterranean salt'
            'tongue", M.A.Spall, P.L.Richardson and J.Price,     '
            'Journal of Marine Research, 51, 797-818, 1993.      '
            '                                                    '
            '      Mike Sparrow for AINCO-Interocean, 1997       '];
helpfun (titleStr,helpStr1) ;


