testsuite::test_iaf_dc - li script for test of iaf_psc_alpha with external DC current
(test_iaf_dc) run -> compare cout with comments in file
test_iaf_dc.sli is a test of a specific feature of the iaf_psc_alpha
model. It is tested at which time and how an external DC current affects
the state of the neuron, the membrane potential in particular.
This is probably the simplest setup demonstrating how an external
continuous function (the DC) can be incorporated into a system with
point event interaction. A general introduction, including examples
not restricted to piecewise constant functions, can be found in [1].
The expected output is documented and briefly commented at the end of
the script.
Cleary, the result of this script is not resolution independent. The
choice of the computation step size determines at which point in time
the current affects the neuron.
There are 2 problems with this script:
1. A network element (here the DC generator) can only change its state
when it performs a computation (update) step t -> t + h.
Thus, the earliest possible time the DC generator can be switched on
is at t=h. This is the default. Therefore, the time of onset depends
on the computation step size.
2. The default delay between the DC generator and the neuron is the minimal
allowed value of 1 h. Therefore, the delay of the current depends on
the computation step size.
A sequence of further test scripts (SeeAlso key below) demonstrates and
verifies how the SLI script can be made independent of the computation
step size. This leads to properly aligned and identical voltage traces
for simulations carried out with different computation step sizes.
[1] Rotter S & Diesmann M (1999) Exact simulation of time-invariant linear
systems with applications to neuronal modeling. Biologial Cybernetics
81:381-402.
February 2004, Diesmann, Gewaltig, Plesser
/var/www/debian/nest/nest-simulator-2.20.0/testsuite/unittests/test_iaf_dc.sli