# Command: testsuite::test_iaf_dc

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Name:

    testsuite::test_iaf_dc - sli script for test of iaf_neuron with external DC current

Synopsis:

    (test_iaf_dc) run -> compare cout with comments in file

Description:

      test_iaf_dc.sli is a test of a specific feature of the iaf_neuron
      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.

References:

      [1] Rotter S & Diesmann M (1999) Exact simulation of time-invariant linear
      systems with applications to neuronal modeling. Biologial Cybernetics
      81:381-402.

      Author:  February 2004, Diesmann, Gewaltig, Plesser

SeeAlso:

- iaf_neuron
- testsuite::test_iaf_dc_aligned
- testsuite::test_iaf_dc_aligned_delay
- testsuite::test_iaf_dc_aligned_stop

Source:

    /opt/conda/conda-bld/nest_1510212701067/work/nest-2.14.0/testsuite/unittests/test_iaf_dc.sli

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