--- /dev/null
+## Copyright (C) 2006,2007,2008 Massimiliano Culpo, Carlo de Falco
+##
+## This file is part of:
+## OCS - A Circuit Simulator for Octave
+##
+## OCS 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.
+##
+## 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 (see the file LICENSE); if not,
+## see <http://www.gnu.org/licenses/>.
+##
+## author: culpo@math.uni-wuppertal.de, Carlo de Falco <cdf _AT_ users.sourceforge.net>
+
+## -*- texinfo -*-
+##
+## @deftypefn{Function File} @
+## {[@var{a},@var{b},@var{c}]=}Mdiode(@var{string},@var{parameters},@
+## @var{parameternames},@var{extvar},@var{intvar},@var{t})
+##
+## SBN file implementing models for diodes.
+##
+## @var{string} is used to select among models. Parameters are listed
+## as inner items. Possible models are:
+##
+## @itemize @minus
+## @item @var{string} = "simple" (Usual exponential diode model)
+## @itemize @minus
+## @item Is -> reverse current
+## @item Vth -> thermal voltage
+## @item Rpar -> parasitic resistance
+## @end itemize
+## @item @var{string} = "PDEsymmetric" (Drift-Diffusion PDE model)
+## @itemize @minus
+## @item len -> diode length
+## @item Nnodes -> number of nodes of 1D grid
+## @item Dope -> doping (abrupt and symmetric)
+## @item toll -> absolute tolerance
+## @item maxit -> max iterations number
+## @item Area -> device area
+## @end itemize
+## @end itemize
+##
+## See the @cite{IFF file format specifications} for details about
+## the output structures.
+##
+## @seealso{prs_iff,asm_initialize_system,asm_build_system}
+## @end deftypefn
+
+function [a,b,c] = Mdiode (string,parameters,parameternames,extvar,intvar,t)
+
+ switch string
+
+ case "simple"
+ Is = 1e-14;
+ Vth = 2.5e-2;
+ Rpar = 1e12;
+ for ii=1:length(parameternames)
+ eval([parameternames{ii} "=" num2str(parameters(ii)) ";"])
+ endfor
+
+ vp = extvar(1);
+ vm = extvar(2);
+
+ I = Is*(exp((vp - vm)/Vth) -1 ) + (vp - vm)/Rpar;
+ geq = Is*exp((vp - vm)/Vth)/Vth + 1/Rpar;
+
+ a = zeros(2);
+ b = [geq -geq; -geq geq];
+ c = [I ; -I] ;
+ break
+
+ case "PDEsymmetric"
+
+ len = 1e-6;
+ Nnodes = 100;
+ Dope=1e23;
+
+ toll = 1e-5;
+ maxit = 100;
+ ptoll = 1e-10;
+ pmaxit = 100;
+
+ Area = 1e-10;
+
+ for ii=1:length(parameternames)
+ eval([parameternames{ii} "=" num2str(parameters(ii)) ";"])
+ endfor
+
+ vp = extvar(1);
+ vm = extvar(2);
+
+ [I,g] = Mpdesympnjunct (len,Dope,vp-vm,Area,Nnodes,toll,maxit,ptoll,pmaxit);
+
+ a = zeros(2);
+ b = [g -g; -g g];
+ c = [I ; -I] ;
+
+ break
+
+ otherwise
+ error(["unknown section:" string])
+ endswitch
+
+endfunction