Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / secs1d-0.0.8 / Utilities / Udriftdiffusion.m

diff --git a/octave_packages/secs1d-0.0.8/Utilities/Udriftdiffusion.m b/octave_packages/secs1d-0.0.8/Utilities/Udriftdiffusion.m
new file mode 100644 (file)
index 0000000..afa6594
--- /dev/null
+++ b/octave_packages/secs1d-0.0.8/Utilities/Udriftdiffusion.m
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+function A=Udriftdiffusion(x,psi,coeff)  
+  
+%A=Udriftdiffusion(x,psi,coeff)
+%
+% Builds the Scharfetter-Gummel approximation
+% of the differential operator - (coeff (n' - n psi'))' 
+%
+
+ ## This file is part of 
+  ##
+  ## SECS1D - A 1-D Drift--Diffusion Semiconductor Device Simulator
+  ## -------------------------------------------------------------------
+  ## Copyright (C) 2004-2007  Carlo de Falco
+  ##
+  ##
+  ##
+  ##  SECS1D 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.
+  ##
+  ##  SECS1D 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 SECS1D; If not, see <http://www.gnu.org/licenses/>.
+  
+  nodes        = x;
+  Nnodes     =length(nodes);
+  
+  elements   = [[1:Nnodes-1]' [2:Nnodes]'];
+  Nelements=size(elements,1);
+  
+  Bcnodes = [1;Nnodes];
+  
+  h=nodes(elements(:,2))-nodes(elements(:,1));
+  
+  c=coeff./h;
+  Bneg=Ubernoulli(-(psi(2:Nnodes)-psi(1:Nnodes-1)),1);
+  Bpos=Ubernoulli( (psi(2:Nnodes)-psi(1:Nnodes-1)),1);
+  
+  
+  d0    = [c(1).*Bneg(1); c(1:end-1).*Bpos(1:end-1)+c(2:end).*Bneg(2:end); c(end)*Bpos(end)];
+  d1    = [1000;-c.* Bpos];
+  dm1   = [-c.* Bneg;1000];
+  
+  A = spdiags([dm1 d0 d1],-1:1,Nnodes,Nnodes);
+  
+  % Last Revision:
+  % $Author: adb014 $
+  % $Date: 2008-02-04 16:26:27 +0100 (man, 04 feb 2008) $
+