symgrid

 SYMGRID   Creates a grid that is symmetric around zero

    The function "mirrors" an existing grid around zero, and append the two
    grids. The original grid must contain positive values. Zero can be
    included (will not be repeated). The output is sorted in ascending order.

 FORMAT   g = symgrid(g)
        
 OUT   g   Extended grid
 IN    g   Positive side of grid. Can include the value zero.

0001 % SYMGRID   Creates a grid that is symmetric around zero
0002 %
0003 %    The function "mirrors" an existing grid around zero, and append the two
0004 %    grids. The original grid must contain positive values. Zero can be
0005 %    included (will not be repeated). The output is sorted in ascending order.
0006 %
0007 % FORMAT   g = symgrid(g)
0008 %
0009 % OUT   g   Extended grid
0010 % IN    g   Positive side of grid. Can include the value zero.
0011 
0012 % 2007-11-29   Created by Patrick Eriksson.
0013 
0014 
0015 function g = symgrid(g)
0016   
0017 if ~isnumeric(g) | ~isvector(g)
0018   error( 'Input variable *g* must be a vector.' );
0019 end
0020 
0021 if any( g < 0 )
0022   error( 'Input variable *g* can not contain negative values.' );
0023 end
0024 
0025 
0026 g = sort(g);
0027 
0028 if g(1) == 0
0029   g = g([end:-1:2 1:end]);
0030 else
0031   g = g([end:-1:1 1:end]);
0032 end
0033 
0034 
0035 %- Make first part negative
0036 %
0037 [u,i] = min(g);
0038 %
0039 g(1:i) = -g(1:i);