The scripts following below reproduce the simulation results presented in the manuscript:
 Victor Matveev (2016) 
Padé Approximation of a Stationary Single-Channel Ca2+ Nanodomain.
 
Biophysical Journal, 111(9): 2062-2074
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It is best to download and place all scripts in the same directory:
 PadeApproximation.m  
MATLAB function 
[Buff, Cal] = PadeApproximation(N, lambda, mu)
computes Pade approximation of order 
N for nondimensionalized Buffer 
and Ca
2+ concentrations for given parameter values 
(lambda, mu), and 
returns symbolic functions of distance 
r=rho from the channel, 
Buff(r)
and 
Cal(r). Note that double-precision round-off errors are possible 
in coefficients. 
 PadeApproximationPlots.m  
MATLAB script 
PadeApproximationPlots produces data in Figure 3 of the 
manuscript, using Pade Approximations generated by the MATLAB function
PadeApproximation(N, lambda, mu) 
 
Finally, below is a simpler (and more stable with respect to future MATLAB version changes) code
computing the 2
nd-order Pade approximant, given by a closed-form solution of a 
quartic polynomial equation system in Eqs. (27) of the manuscript:
 PadeApproximationQuadraticExplicit.m  
MATLAB function 
[Buff, Cal] = PadeApproximationQuadraticExplicit(lambda, mu, rr, plotFlag)
computes 2
nd-order Pade approximation for nondimensionalized Buffer 
and Ca
2+ concentrations for given parameter values 
(lambda, mu), and 
returns symbolic functions of distance from the channel, 
Buff(r)
and 
Cal(r). The array of distances 
rr will be populated automatically
if an empty array is passed. Set 
plotFlag to a non-zero value to see
a plot of buffer concentration.
Supported in part by the 
National Science Foundation grant
DMS 1517085 to Victor Matveev
Victor Matveev
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Last modified: Apr 2, 2019