Hi Søren,
I would like to contribute with the divergence function. This function
is used to compute divergence of vector field and is not included in
Octave's distribution. So, could you please give a suggestion on where
to locate the file within the repository?
Thanks a lot.
Regards,
Javier
## Copyright (C) 2009 Javier Enciso <[email protected]>
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 3 of the License, or
## (at your option) any later version.
##
## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with this program; if not, see
## <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {Function file} {} divergence (@var{X}, @var{Y}, @var{Z},
@var{U}, @var{V}, @var{W})
## @deftypefnx {Function file} {} divergence (@var{U}, @var{V}, @var{W})
## @deftypefnx {Function file} {} divergence (@var{X}, @var{Y}, @var{U},
@var{V})
## @deftypefnx {Function file} {} divergence (@var{U}, @var{V})
## Compute divergence of vector field.
##
## @code{divergence(X, Y, Z, U, V, W)} computes the divergence of a 3-D vector
field
## @var{U}, @var{V}, @var{W} at the points @var{X}, @var{Y}, @var{Z}.
Coordinate points
## must preserve the given order and define a 3-dimensional grid.
##
## If @var{X}, @var{Y}, and @var{Z} are omitted, @code{divergence(U,V,W)}
assumes
## that the coordinates are given by the expression @code{[X Y Z] =
meshgrid(1:n,1:m,1:p)}
## where @code{[m,n,p] = size(U)}.
##
## @code{divergence(X, Y, U, V)} computes the divergence of a 2-D vector field
@var{U},
## @var{V} at the points @var{X}, @var{Y}. Coordinate points must preserve the
given order
## and define a 2-dimensional grid.
##
## If @var{X} and @var{Y} are omitted, @code{divergence(U,V)} assumes that the
## coordinate points @var{X} and @var{Y} are given by the expression @code{[X
Y] =
## meshgrid(1:n,1:m)} where @code{[m,n] = size(U)}.
## @end deftypefn
function [div] = divergence(varargin)
if nargin < 2
print_usage();
return
elseif nargin == 2
u = varargin{1};
v = varargin{2};
if uvcheck(u,v) == 1
[du dump] = gradient(u);
[dump dv] = gradient(v);
div = du + dv;
return
end
elseif nargin == 3
u = varargin{1};
v = varargin{2};
w = varargin{3};
if uvwcheck(u,v,w) == 1
[du dump dump] = gradient(u);
[dump dv dump] = gradient(v);
[dump dump dw] = gradient(w);
div = du + dv + dw;
return
end
elseif nargin == 4
x = varargin{1};
y = varargin{2};
u = varargin{3};
v = varargin{4};
if xyuvcheck(x,y,u,v) == 1
[du dump] = gradient(u);
[dump dv] = gradient(v);
[dx dump] = gradient(x);
[dump dy] = gradient(y);
div = du./dx + dv./dy;
return
end
elseif nargin == 6
x = varargin{1};
y = varargin{2};
z = varargin{3};
u = varargin{4};
v = varargin{5};
w = varargin{6};
if xyzuvwcheck(x,y,z,u,v,w) == 1
[du dump dump] = gradient(u);
[dump dv dump] = gradient(v);
[dump dump dw] = gradient(w);
[dx dump dump] = gradient(x);
[dump dy dump] = gradient(y);
[dump dump dz] = gradient(z);
div = du./dx + dv./dy + dw./dz;
return
end
else
print_usage();
return
end
function [msg] = uvcheck(u, v)
d = zeros(1,2);
d(1) = ndims(u);
d(2) = ndims(v);
if find(d(1,:) ~= 2)
error('Matrices must have 2 dimensions');
end
d = zeros(2);
d(1,:) = size(u);
d(2,:) = size(v);
if find(d(1,:) == d(2,:) == 0)
error('Size of matrices must be equal');
end
msg = 1;
function [msg] = xyuvcheck(x, y, u, v)
d = zeros(1,4);
d(1) = ndims(x);
d(2) = ndims(y);
d(3) = ndims(u);
d(4) = ndims(v);
if find(d(1,:) ~= 2)
error('Matrices must have 2 dimensions');
end
d = zeros(4,2);
d(1,:) = size(x);
d(2,:) = size(y);
d(3,:) = size(u);
d(4,:) = size(v);
for m = 1:3
if find(d(m,:) == d(m+1,:) == 0)
error('Size of matrices must be equal');
end
end
msg = 1;
function [msg] = uvwcheck(u, v, w)
d = zeros(1, 3);
d(1) = ndims(u);
d(2) = ndims(v);
d(3) = ndims(w);
if find(d(1,:) ~= 3)
error('Matrices must have 3 dimensions');
end
d = zeros(3);
d(1,:) = size(u);
d(2,:) = size(v);
d(3,:) = size(w);
for m = 1:2
if find(d(m,:) == d(m+1,:) == 0)
error('Size of matrices must be equal');
end
end
msg = 1;
function [msg] = xyzuvwcheck(x, y, z, u, v, w)
d = zeros(1,6);
d(1) = ndims(x);
d(2) = ndims(y);
d(3) = ndims(z);
d(4) = ndims(u);
d(5) = ndims(v);
d(6) = ndims(w);
if find(d(1,:) ~= 3)
error('Matrices must have 3 dimensions');
end
d = zeros(6,3);
d(1,:) = size(x);
d(2,:) = size(y);
d(3,:) = size(z);
d(4,:) = size(u);
d(5,:) = size(v);
d(6,:) = size(w);
for m = 1:5
if find(d(m,:) == d(m+1,:) == 0)
error('Size of matrices must be equal');
end
end
msg = 1;------------------------------------------------------------------------------
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