testsuite::test_iaf_psp_normalized - check if PSP can be normalized
(test_iaf_psp_normalized) run -> compare response with desired outcome  


The script computes the peak location of the PSP analytically for a
neuron model with an alpha-shaped post-synaptic current (PSC) [1]. In case
the GNU Scientific Library (GSL) is not present the peak location is
found by searching for the root of the derivative of the PSP. We then
compute the peak value for a PSC with unit amplitude and show how the
synaptic weight can be adjusted to cause a PSP of a specific
amplitiude. Finally, we check whether the simulation indeed generates
a PSP of the desired amplitude.

In application code the test for the availability of the GSL is not
necessary because NEST has a built in version of the LambertWm1 which
automatically replaces the GSL function if required. This removes the
need to specify the derivative of the function of interest, here the
PSP, in application code. A further alternative is used in
test_lambertw where knowledge of the range of values of the
non-principal branch of the Lambert-W function [-1,-\infty) is
exploited to find the inverse of x*exp(x) by bisectioning.

[1] Rotter S & Diesmann M (1999) Exact simulation of time-invariant linear
systems with applications to neuronal modeling. Biologial Cybernetics
[2] Galassi, M., Davies, J., Theiler, J., Gough, B., Jungman, G., Booth, M.,
& Rossi, F. (2006). GNU Scientific Library Reference Manual (2nd Ed.).
Network Theory Limited.

Author: July 2009, Diesmann
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