Constants

Python

The following mathematical and physical constants are available through the n module:

Mathematical and Physical Constants

Constant	Value	Description
n.PI	3.14159265358979323846
n.E	2.71828182845904523536
n.GAMMA	0.57721566490153286060	Euler’s constant
n.DEG	57.29577951308232087680	Degrees per radian
n.PHI	1.61803398874989484820	Golden ratio
n.FARADAY	96485.3321233100141	Modern value, derived from mole and electron charge
n.R	8.3144626181532395	Modern value, derived from Boltzmann constant and mole
n.Avogadro_constant	6.02214076e23	CODATA 2018 value, introduced in version 8.0

As of Version 8.0 (circa October, 2020) modern units are the default.

Warning

Constants are not treated specially by the interpreter and may be changed with assignment statements. However a change of FARADAY, R, or Avogadro_constant generates a warning message (default once). Python warning messages can be managed with import warnings; warnings.filterwarnings(action) where useful actions are "error", "ignore", "always", or "once". If assignment takes place due to execution of a hoc interpreter statement, the warning occurs only once but cannot be avoided.

HOC

The following mathematical and physical constants are built-in to the HOC interpreter:

Mathematical and Physical Constants

Constant	Value	Description
PI	3.14159265358979323846
E	2.71828182845904523536
GAMMA	0.57721566490153286060	Euler’s constant
DEG	57.29577951308232087680	Degrees per radian
PHI	1.61803398874989484820	Golden ratio
FARADAY	96485.3321233100141	Modern value, derived from mole and electron charge
R	8.3144626181532395	Modern value, derived from Boltzmann constant and mole
Avogadro_constant	6.02214076e23	CODATA 2018 value, introduced in version 8.0

As of Version 8.0 (circa October, 2020) modern units are the default.

Note

By default, HOC displays less digits of precision than shown here.

Warning

Constants are not treated specially by the interpreter and may be changed with assignment statements. However a change of FARADAY, R, or Avogadro_constant generates a warning message (default once). Python warning messages can be managed with import warnings; warnings.filterwarnings(action) where useful actions are "error", "ignore", "always", or "once". If assignment takes place due to execution of a hoc interpreter statement, the warning occurs only once but cannot be avoided.

MATLAB

The following mathematical and physical constants are available through the n object (where n = neuron.launch()):

Mathematical and Physical Constants

Constant	Value	Description
n.PI	3.14159265358979323846
n.E	2.71828182845904523536
n.GAMMA	0.57721566490153286060	Euler’s constant
n.DEG	57.29577951308232087680	Degrees per radian
n.PHI	1.61803398874989484820	Golden ratio
n.FARADAY	96485.3321233100141	Modern value, derived from mole and electron charge
n.R	8.3144626181532395	Modern value, derived from Boltzmann constant and mole
n.Avogadro_constant	6.02214076e23	CODATA 2018 value, introduced in version 8.0

As of Version 8.0 (circa October, 2020) modern units are the default.

Warning

Constants are not treated specially by the interpreter and may be changed with assignment statements. However a change of FARADAY, R, or Avogadro_constant generates a warning message (default once). Python warning messages can be managed with import warnings; warnings.filterwarnings(action) where useful actions are "error", "ignore", "always", or "once". If assignment takes place due to execution of a hoc interpreter statement, the warning occurs only once but cannot be avoided.