"""
Module implementing Brian's refractory mechanism.
"""
from brian2.units.fundamentalunits import DIMENSIONLESS
from brian2.units.allunits import second
from .equations import (Equations, SingleEquation, DIFFERENTIAL_EQUATION,
PARAMETER, Expression, BOOLEAN)
__all__ = ['add_refractoriness']
[docs]def check_identifier_refractory(identifier):
"""
Check that the identifier is not using a name reserved for the refractory
mechanism. The reserved names are `not_refractory`, `refractory`,
`refractory_until`.
Parameters
----------
identifier : str
The identifier to check.
Raises
------
ValueError
If the identifier is a variable name used for the refractory mechanism.
"""
if identifier in ('not_refractory', 'refractory', 'refractory_until'):
raise SyntaxError(f"The name '{identifier}' is used in the refractory mechanism "
f" and should not be used as a variable "
f"name.")
Equations.register_identifier_check(check_identifier_refractory)
[docs]def add_refractoriness(eqs):
"""
Extends a given set of equations with the refractory mechanism. New
parameters are added and differential equations with the "unless refractory"
flag are changed so that their right-hand side is 0 when the neuron is
refractory (by multiplication with the ``not_refractory`` variable).
Parameters
----------
eqs : `Equations`
The equations without refractory mechanism.
Returns
-------
new_eqs : `Equations`
New equations, with added parameters and changed differential
equations having the "unless refractory" flag.
"""
new_equations = []
# replace differential equations having the active flag
for eq in eqs.values():
if eq.type == DIFFERENTIAL_EQUATION and 'unless refractory' in eq.flags:
# the only case where we have to change anything
new_code = f"int(not_refractory)*({eq.expr.code})"
new_equations.append(SingleEquation(DIFFERENTIAL_EQUATION,
eq.varname, eq.dim,
expr=Expression(new_code),
flags=eq.flags))
else:
new_equations.append(eq)
# add new parameters
new_equations.append(SingleEquation(PARAMETER, 'not_refractory',
DIMENSIONLESS, var_type=BOOLEAN))
new_equations.append(SingleEquation(PARAMETER, 'lastspike', second.dim))
return Equations(new_equations)