Name: testsuite::test_iaf_fudge - li script to test normalization of PSP for iaf_psc_alpha model

Synopsis:

(test_iaf_fudge) run -&gt; compares response to spike input step with reference data


Description:

The peak time of the postsynaptic potential (PSP) is calculated using 
the LambertW function. The theoretical peak voltage amplitude for a 
postsynaptic current of amplitude 1pA is then used to adjust the 
synaptic weight such that a PSP of amplitude 1mV is generated.  The 
success of this approach is verified by comparing the theoretical 
value with the result of a simulation where a single spike is sent to 
the neuron. 
The name of this test script has a historical explanation. Prior to 
July 2009 the analytical expression for the peak time of the PSP was 
not known to the NEST developers. Therefore the normalization factor 
required to adjust the PSP amplitude was computed by root finding 
outside of NEST. The factor was called "fudge" in examples and 
application code. The root finding was not done in NEST because infix 
mathematical notation only become available in SLI in January 
2009. The name "fudge" indicated that the origin of this value was not 
obvious from the simulation scripts and usage was inherently dangerous 
because a change of the time constants of the neuron model would 
invalidate the value of "fudge".


Author:

July 2009, Helias


SeeAlso:

iaf_psc_alpha
testsuite::test_iaf
testsuite::test_lambertw
LambertWm1

Source:

/var/www/debian/nest/nest-simulator-2.20.0/testsuite/unittests/test_iaf_fudge.sli
