1## Copyright (C) 2006,2007,2008,2009,2010 Carlo de Falco, Massimiliano Culpo 2## 3## This file is part of: 4## BIM - Diffusion Advection Reaction PDE Solver 5## 6## BIM is free software; you can redistribute it and/or modify 7## it under the terms of the GNU General Public License as published by 8## the Free Software Foundation; either version 2 of the License, or 9## (at your option) any later version. 10## 11## BIM is distributed in the hope that it will be useful, 12## but WITHOUT ANY WARRANTY; without even the implied warranty of 13## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14## GNU General Public License for more details. 15## 16## You should have received a copy of the GNU General Public License 17## along with BIM; If not, see <http://www.gnu.org/licenses/>. 18## 19## author: Carlo de Falco <cdf _AT_ users.sourceforge.net> 20## author: Massimiliano Culpo <culpo _AT_ users.sourceforge.net> 21 22## -*- texinfo -*- 23## 24## @deftypefn {Function File} {[@var{gx}, @var{gy}, @var{gz}]} = @ 25## bim3c_pde_gradient(@var{mesh},@var{u}) 26## 27## Compute the gradient of the piecewise linear conforming scalar 28## function @var{u}. 29## 30## @seealso{bim3c_global_flux} 31## @end deftypefn 32 33function [gx, gy, gz] = bim3c_pde_gradient (mesh, u) 34 35 ## Check input 36 if (nargin != 2) 37 error("bim3c_pde_gradient: wrong number of input parameters."); 38 elseif (! (isstruct (mesh) && isfield (mesh,"p")) && 39 isfield (mesh, "t") && isfield(mesh, "e")) 40 error ("bim3c_pde_gradient: first input is not a valid mesh structure."); 41 endif 42 43 nnodes = columns (mesh.p); 44 45 if (numel (u) != nnodes) 46 error ("bim3c_pde_gradient: length(u) != nnodes."); 47 endif 48 49 gx = sum (squeeze (mesh.shg(1,:,:)) .* u(mesh.t(1:4,:)), 1); 50 gy = sum (squeeze (mesh.shg(2,:,:)) .* u(mesh.t(1:4,:)), 1); 51 gz = sum (squeeze (mesh.shg(3,:,:)) .* u(mesh.t(1:4,:)), 1); 52 53endfunction 54