When
running a simulation we often want to use a small time step for the
integration, but we also want to conserve disk space when the data
is finally output. The Print Step Size
directive in the .setup file allows us to alter the frequency that
samples are output to data files. However, as shown below aliasing will
occur that can truncate spikes. NeuronetExperimenter allows the user to specify a strategy for outputting the data using the Alias directive. See the examples below: alias-actual.setup:
... Dt 0.05 Print Step Size 1 ...
alias-none.setup:
... Dt 0.05 Print Step Size 10 Alias none# This setting is the default and does not need to be explicitly set ...
alias-anti.setup:
... Dt 0.05 Print Step Size 10 Alias anti ...
alias-over.setup:
... Dt 0.05 Print Step Size 10 Alias over ...
Notice
that the first example and the last example look very similar,
while the last simulation runs much faster because 1/10 the amount of
samples are written to the disk. The Alias over example reports local extema as its outputting over the interval of timesteps between the output samples. In general, Alias over should be used if Print Step Size
is greater than 1 to get qualitatively similar results, but it is
important to understand that the results are not exactly what the
simulator is calculating.
