Classical Hodgkin-Huxley model for Squid Giant Axon.
% Except v polarity reversed and rest potential shifted to -65.
% cf. Hansel, Mato, and Meunier, Europhys. Lett. 23:367-372, 1993.

init v=-65, h=0.596, n=0.318, m=0.053

params iapp=0, cm=1
params gnabar=120, gkbar=36, gl=0.3
params vna=50, vk=-77, vl=-54.4

am   = 0.1*(v+40)/( 1 - exp(-(v+40)/10) )
bm   = 4*exp(-(v+65)/18)
minf = am/(am+bm)
taum = 1/(am+bm)

ah   = 0.07*exp(-(v+65)/20)
bh   = 1/( 1 + exp(-(v+35)/10) )
hinf = ah/(ah+bh)
tauh = 1/(ah+bh)

an   = 0.01*(v + 55)/(1 - exp(-(v + 55)/10))
bn   = 0.125*exp(-(v + 65)/80)
ninf = an/(an+bn)
taun = 1/(an+bn)

ina = gnabar * m^3 * h * (v-vna)
ik  = gkbar * n^4 * (v-vk)
il  = gl * (v-vl)

v' =  ( iapp - ina - ik - il ) / cm
h' =  (hinf - h)/tauh
n' =  (ninf - n)/taun
m' =  (minf - m)/taum

@ maxstor=12000
@ total=100, dt=0.5, bounds=10000
@ method=gear, toler=0.0000001, dtmin=0.000001, dtmax=1
@ xlo=0, xhi=100, ylo=-80, yhi=30
# AUTO stuff
@ Nmax=500, NPr=200, ParMin=-50, ParMax=300
@ AutoXMin=-5, AutoXMax=190
@ AutoYMin=-80, AutoYMax=35
done