/usr/share/octave/packages/bim-1.1.5/bim3c_pde_gradient.m is in octave-bim 1.1.5-4.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 | ## Copyright (C) 2006,2007,2008,2009,2010 Carlo de Falco, Massimiliano Culpo
##
## This file is part of:
## BIM - Diffusion Advection Reaction PDE Solver
##
## BIM 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 2 of the License, or
## (at your option) any later version.
##
## BIM 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 BIM; If not, see <http://www.gnu.org/licenses/>.
##
## author: Carlo de Falco <cdf _AT_ users.sourceforge.net>
## author: Massimiliano Culpo <culpo _AT_ users.sourceforge.net>
## -*- texinfo -*-
##
## @deftypefn {Function File} {[@var{gx}, @var{gy}, @var{gz}]} = @
## bim3c_pde_gradient(@var{mesh},@var{u})
##
## Compute the gradient of the piecewise linear conforming scalar
## function @var{u}.
##
## @seealso{bim3c_global_flux}
## @end deftypefn
function [gx, gy, gz] = bim3c_pde_gradient (mesh, u)
## Check input
if (nargin != 2)
error("bim3c_pde_gradient: wrong number of input parameters.");
elseif (! (isstruct (mesh) && isfield (mesh,"p")) &&
isfield (mesh, "t") && isfield(mesh, "e"))
error ("bim3c_pde_gradient: first input is not a valid mesh structure.");
endif
nnodes = columns (mesh.p);
if (numel (u) != nnodes)
error ("bim3c_pde_gradient: length(u) != nnodes.");
endif
gx = sum (squeeze (mesh.shg(1,:,:)) .* u(mesh.t(1:4,:)), 1);
gy = sum (squeeze (mesh.shg(2,:,:)) .* u(mesh.t(1:4,:)), 1);
gz = sum (squeeze (mesh.shg(3,:,:)) .* u(mesh.t(1:4,:)), 1);
endfunction
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