sigma_geo

 Generate a geometric sigma coordinate distribution.

 Mobj = sigma_gen(nlev, p_sigma)

 DESCRIPTION:
   Generate a geometric vertical sigma coordinate distribution.

 INPUT:
   nlev:       Number of sigma levels (layers + 1)
   p_sigma:    1 for uniform sigma layers, 2 for parabolic function. See
               page 308-309 in the FVCOM manual for examples.

 OUTPUT:
   dist:       Geometric vertical sigma coordinate distribution.

 EXAMPLE USAGE:
   Mobj = read_sigma(21, 2.0)

 Author(s):
   Geoff Cowles (University of Massachusetts Dartmouth)
   Pierre Cazenave (Plymouth Marine Laboratory)

 Revision history
   2013-04-23 Added help on the function and reformatted the code to
   remove the FORTRAN in the else block.

0001 function dist = sigma_geo(nlev, p_sigma)
0002 % Generate a geometric sigma coordinate distribution.
0003 %
0004 % Mobj = sigma_gen(nlev, p_sigma)
0005 %
0006 % DESCRIPTION:
0007 %   Generate a geometric vertical sigma coordinate distribution.
0008 %
0009 % INPUT:
0010 %   nlev:       Number of sigma levels (layers + 1)
0011 %   p_sigma:    1 for uniform sigma layers, 2 for parabolic function. See
0012 %               page 308-309 in the FVCOM manual for examples.
0013 %
0014 % OUTPUT:
0015 %   dist:       Geometric vertical sigma coordinate distribution.
0016 %
0017 % EXAMPLE USAGE:
0018 %   Mobj = read_sigma(21, 2.0)
0019 %
0020 % Author(s):
0021 %   Geoff Cowles (University of Massachusetts Dartmouth)
0022 %   Pierre Cazenave (Plymouth Marine Laboratory)
0023 %
0024 % Revision history
0025 %   2013-04-23 Added help on the function and reformatted the code to
0026 %   remove the FORTRAN in the else block.
0027 
0028 dist = nan(1, nlev);
0029 
0030 kb = nlev;
0031 
0032 if p_sigma == 1
0033     for k = 1:nlev
0034         dist(k) = -((k-1)/(kb-1))^p_sigma;
0035     end
0036 else
0037     for k = 1:floor((kb+1)/2)
0038         dist(k) = -((k-1)/((kb+1)/2-1))^p_sigma/2;
0039     end
0040     for k = floor((kb+1)/2)+1:kb
0041         dist(k) = ((kb-k)/((kb+1)/2-1))^p_sigma/2-1.0;
0042     end
0043 end