COMMENT
I added area in LON.._DIF.. expression and buffering
Longitudinal diffusion of sodium (with buffering coefficient f)
(equivalent modified euler with standard method and
equivalent to diagonalized linear solver with CVODE )
LONGITUDINAL_DIFFUSION D*PI*diam*diam/4 {nai}
ENDCOMMENT
NEURON {
SUFFIX nadifl
USEION na READ ina WRITE nai
RANGE D,nainit,f
}
UNITS {
(mM) = (milli/liter)
(um) = (micron)
FARADAY = (faraday) (coulomb)
PI = (pi) (1)
}
PARAMETER {
D = .6 (um2/ms)
nainit = 3.54 (mM)
f = 1.00
}
ASSIGNED {
ina (milliamp/cm2)
diam (um)
}
STATE {
nai (mM) <1e-4>
}
BREAKPOINT {
SOLVE state METHOD sparse
}
INITIAL{
nai=nainit
}
KINETIC state {
COMPARTMENT PI*diam*diam/4 {nai}
~ nai << (-f*ina*PI*diam*(1e4)/(FARADAY))
}