/*
 * The Polynomial Model
 * 
 * Model Status
 * 
 * This is the original unchecked version of the model imported
 * from the previous CellML model repository, 24-Jan-2006.
 * 
 * Model Structure
 * 
 * Often it is not necessary to model the ionic currents of a cell
 * with the accuracy and complexity inherent in the biophysically
 * based models. With a view to investigating phenomena on a larger
 * spatial and temporal scale, several ionic current models have
 * been developed that do not seek to model subcellular processes
 * but only to provide an action potential at a minimal computational
 * cost.
 * 
 * The simplest of these models is a polynomial model that just
 * uses one variable. It was developed by Hunter, McNaughton and
 * Noble in 1975 and it is commonly used to track cellular depolarisation.
 * However, it does not attempt to model repolarisation. The lowest
 * order polynomial model is the cubic model which can be extended
 * to use a higher order polynomial. As there is only a single
 * variable, the model is very fast to calculate and therefore
 * it may be used on large geometries.
 * 
 * The complete original paper reference is cited below:
 * 
 * Analytical models of propagation in excitable cells, Hunter,
 * P.J., McNaughton, P.A. and Noble, D., 1975, Prog. Biophys. molec.
 * Biol., 30, 99-144. PubMed ID: 792954
 * 
 * The raw CellML description of the simplified cardiac myocyte
 * models can be downloaded in various formats as described in
 * . For an example of a more complete documentation for an electrophysiological
 * model, see The Hodgkin-Huxley Squid Axon Model, 1952.
 */

import nsrunit;
// Warning: unit conversion turned off due to unit errors in 2 equation(s)
unit conversion off;
unit mV=.001 kilogram^1*meter^2*second^(-3)*ampere^(-1);
unit uA_per_mmsq=1  dimensionless;
unit uF_per_mmsq=1  dimensionless;
unit mS_per_mmsq=1  dimensionless;
unit ms=.001 second^1;
//Warning:  unit uFpmmsq unknown; assuming it is a fundamental unit.
unit uFpmmsq = fundamental;
//Warning:  unit mSpmmsq unknown; assuming it is a fundamental unit.
unit mSpmmsq = fundamental;
//Warning:  unit uApmmsq unknown; assuming it is a fundamental unit.
unit uApmmsq = fundamental;

math main {
	//Warning:  the following variables were set 'extern' or given
	//  an initial value of '0' because the model would otherwise be
	//  underdetermined:  interface.Cm, Vm_rest, Vm_plateau, Vm_threshold,
	//  Vm_initial, membrane_conductance, Istim, current.Cm
	realDomain t ms;
	t.min=0;
	extern t.max;
	extern t.delta;
	extern real interface.Cm uFpmmsq;
	extern real Vm_rest mV;
	extern real Vm_plateau mV;
	extern real Vm_threshold mV;
	extern real Vm_initial mV;
	extern real membrane_conductance mSpmmsq;
	extern real Istim uApmmsq;
	real I(t) uApmmsq;
	extern real current.Cm uFpmmsq;
	real plateau mV;
	real threshold mV;
	real phi(t) mV;
	real Vm(t) mV;
	when(t=t.min) Vm=Vm_initial;

	// <component name="interface">

	// <component name="membrane">
	Vm:t=((Istim-I)/interface.Cm);

	// <component name="current">
	plateau=(Vm_plateau-Vm_rest);
	threshold=(Vm_threshold-Vm_rest);
	phi=(Vm-Vm_rest);
	I=(membrane_conductance*phi*(1-phi/threshold)*(1-phi/plateau));
}