%filename: in_mhnv.m
%this script simulates holding the
%voltage constant for a long time
%prior to t=0 at the value v=vhold,
%and then applying a current shock
%at t=0 to step the voltage
%to a new level, v=vstart.
%The gating variables m,h,n
%cannot change suddenly and therefore
%remain constant during the current shock.
%
%simulate time prior to t=0:
v=vhold
%set m,h,n equal to their steady values
%under constant-v conditions:
m=alpham(v)/(alpham(v)+betam(v))
h=alphah(v)/(alphah(v)+betah(v))
n=alphan(v)/(alphan(v)+betan(v))
%
%now let voltage jump to its value
%just after t=0, without making
%any further change in m,h,n:
v=vstart