| Description: |
A multimeter records a user-defined set of state variables from connected nodes to memory,
file or stdout.
The multimeter must be configured with the list of variables to record
from, otherwise it will not record anything. The /recordables property
of a neuron model shows which quantities can be recorded with a multimeter.
A single multimeter should only record from neurons of the same basic
type (e.g. /iaf_cond_alpha and any user-defined models derived from it
using CopyModel). If the defaults or status dictionary of a model neuron
does not contain a /recordables entry, it is not ready for use with
multimeter.
By default, multimeters record values once per ms. Set the parameter /interval to
change this. The recording interval cannot be smaller than the resolution.
Results are returned in the /events entry of the status dictionary. For
each recorded quantity, a vector of doubles is returned. The vector has the
same name as the /recordable. If /withtime is set, times are given in the
/times vector in /events.
Accumulator mode:
Multimeter can operate in accumulator mode. In this case, values for all recorded
variables are added across all recorded nodes (but kept separate in time). This can
be useful to record average membrane potential in a population.
To activate accumulator mode, either set /to_accumulator to true, or set
/record_to [ /accumulator ]. In accumulator mode, you cannot record to file,
to memory, to screen, with GID or with weight. You must activate accumulator mode
before simulating. Accumulator data is never written to file. You must extract it
from the device using GetStatus.
Note:
- The set of variables to record and the recording interval must be set
BEFORE the multimeter is connected to any node, and cannot be changed
afterwards.
- A multimeter cannot be frozen.
- If you record with multimeter in accumulator mode and some of the nodes
you record from and others are not, data will only be collected from the
unfrozen nodes. Most likely, this will lead to confusing results, so
you should not use multimeter with frozen nodes.
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