units package

The unit system.

Exported members: pamp, namp, uamp, mamp, amp, kamp, Mamp, Gamp, Tamp, kelvin, kilogram, pmetre, nmetre, umetre, mmetre, metre, kmetre, Mmetre, Gmetre, Tmetre, pmeter, nmeter, umeter, mmeter, meter … (218 more members)

allunits module


Instead edit the template:


Exported members: metre, meter, kilogram, second, amp, ampere, kelvin, mole, mol, candle, kilogramme, gram, gramme, molar, radian, steradian, hertz, newton, pascal, joule, watt, coulomb, volt, farad, ohm … (2045 more members)


celsius A dummy object to raise errors when celsius is used.

constants module

A module providing some physical units as Quantity objects. Note that these units are not imported by wildcard imports (e.g. from brian2 import *), they have to be imported explicitly. You can use import ... as ... to import them with shorter names, e.g.:

from brian2.units.constants import faraday_constant as F

The available constants are:

Constant Symbol(s) Brian name Value
Avogadro constant \(N_A, L\) avogadro_constant \(6.022140857\times 10^{23}\,\mathrm{mol}^{-1}\)
Boltzmann constant \(k\) boltzmann_constant \(1.38064852\times 10^{-23}\,\mathrm{J}\,\mathrm{K}^{-1}\)
Electric constant \(\epsilon_0\) electric_constant \(8.854187817\times 10^{-12}\,\mathrm{F}\,\mathrm{m}^{-1}\)
Electron mass \(m_e\) electron_mass \(9.10938356\times 10^{-31}\,\mathrm{kg}\)
Elementary charge \(e\) elementary_charge \(1.6021766208\times 10^{-19}\,\mathrm{C}\)
Faraday constant \(F\) faraday_constant \(96485.33289\,\mathrm{C}\,\mathrm{mol}^{-1}\)
Gas constant \(R\) gas_constant \(8.3144598\,\mathrm{J}\,\mathrm{mol}^{-1}\,\mathrm{K}^{-1}\)
Magnetic constant \(\mu_0\) magnetic_constant \(12.566370614\times 10^{-7}\,\mathrm{N}\,\mathrm{A}^{-2}\)
Molar mass constant \(M_u\) molar_mass_constant \(1\times 10^{-3}\,\mathrm{kg}\,\mathrm{mol}^{-1}\)
0°C   zero_celsius \(273.15\,\mathrm{K}\)

fundamentalunits module

Defines physical units and quantities

Quantity Unit Symbol
Length metre m
Mass kilogram kg
Time second s
Electric current ampere A
Temperature kelvin K
Quantity of substance mole mol
Luminosity candle cd

Exported members: DimensionMismatchError, get_or_create_dimension(), get_dimensions(), is_dimensionless(), have_same_dimensions(), in_unit(), in_best_unit(), Quantity, Unit, register_new_unit(), check_units(), is_scalar_type(), get_unit()


Dimension(dims) Stores the indices of the 7 basic SI unit dimension (length, mass, etc.).
DimensionMismatchError(description, *dims) Exception class for attempted operations with inconsistent dimensions.
Quantity A number with an associated physical dimension.
Unit(value[, dim, scale, name, dispname, …]) A physical unit.
UnitRegistry() Stores known units for printing in best units.


check_units(**au) Decorator to check units of arguments passed to a function
fail_for_dimension_mismatch(obj1[, obj2, …]) Compare the dimensions of two objects.
get_dimensions(obj) Return the dimensions of any object that has them.
get_or_create_dimension(*args, **kwds) Create a new Dimension object or get a reference to an existing one.
get_unit(d) Find an unscaled unit (e.g.
get_unit_for_display(d) Return a string representation of an appropriate unscaled unit or '1' for a dimensionless quantity.
have_same_dimensions(obj1, obj2) Test if two values have the same dimensions.
in_best_unit(x[, precision]) Represent the value in the “best” unit.
in_unit(x, u[, precision]) Display a value in a certain unit with a given precision.
is_dimensionless(obj) Test if a value is dimensionless or not.
is_scalar_type(obj) Tells you if the object is a 1d number type.
quantity_with_dimensions(floatval, dims) Create a new Quantity with the given dimensions.
register_new_unit(u) Register a new unit for automatic displaying of quantities
wrap_function_change_dimensions(func, …) Returns a new function that wraps the given function func so that it changes the dimensions of its input.
wrap_function_dimensionless(func) Returns a new function that wraps the given function func so that it raises a DimensionMismatchError if the function is called on a quantity with dimensions (excluding dimensionless quantities).
wrap_function_keep_dimensions(func) Returns a new function that wraps the given function func so that it keeps the dimensions of its input.
wrap_function_remove_dimensions(func) Returns a new function that wraps the given function func so that it removes any dimensions from its input.


DIMENSIONLESS The singleton object for dimensionless Dimensions.
additional_unit_register UnitRegistry containing additional units (newton*metre, farad / metre, …)
standard_unit_register UnitRegistry containing all the standard units (metre, kilogram, um2…)
user_unit_register UnitRegistry containing all units defined by the user

stdunits module

Optional short unit names

This module defines the following short unit names:

mV, mA, uA (micro_amp), nA, pA, mF, uF, nF, nS, mS, uS, ms, Hz, kHz, MHz, cm, cm2, cm3, mm, mm2, mm3, um, um2, um3

Exported members: mV, mA, uA, nA, pA, pF, uF, nF, nS, uS, mS, ms, us, Hz, kHz, MHz, cm, cm2, cm3, mm, mm2, mm3, um, um2, um3 … (3 more members)

unitsafefunctions module

Unit-aware replacements for numpy functions.

Exported members: log(), log10(), exp(), expm1(), log1p(), exprel(), sin(), cos(), tan(), arcsin(), arccos(), arctan(), sinh(), cosh(), tanh(), arcsinh(), arccosh(), arctanh(), diagonal(), ravel(), trace(), dot(), where(), ones_like(), zeros_like() … (2 more members)


arange([start,] stop[, step,][, dtype, like]) Return evenly spaced values within a given interval.
arccos(x, /[, out, where, casting, order, …]) Trigonometric inverse cosine, element-wise.
arccosh(x, /[, out, where, casting, order, …]) Inverse hyperbolic cosine, element-wise.
arcsin(x, /[, out, where, casting, order, …]) Inverse sine, element-wise.
arcsinh(x, /[, out, where, casting, order, …]) Inverse hyperbolic sine element-wise.
arctan(x, /[, out, where, casting, order, …]) Trigonometric inverse tangent, element-wise.
arctanh(x, /[, out, where, casting, order, …]) Inverse hyperbolic tangent element-wise.
cos(x, /[, out, where, casting, order, …]) Cosine element-wise.
cosh(x, /[, out, where, casting, order, …]) Hyperbolic cosine, element-wise.
diagonal(a[, offset, axis1, axis2]) Return specified diagonals.
dot(a, b[, out]) Dot product of two arrays.
exp(x, /[, out, where, casting, order, …]) Calculate the exponential of all elements in the input array.
linspace(start, stop[, num, endpoint, …]) Return evenly spaced numbers over a specified interval.
log(x, /[, out, where, casting, order, …]) Natural logarithm, element-wise.
ravel(a[, order]) Return a contiguous flattened array.
sin(x, /[, out, where, casting, order, …]) Trigonometric sine, element-wise.
sinh(x, /[, out, where, casting, order, …]) Hyperbolic sine, element-wise.
tan(x, /[, out, where, casting, order, …]) Compute tangent element-wise.
tanh(x, /[, out, where, casting, order, …]) Compute hyperbolic tangent element-wise.
trace(a[, offset, axis1, axis2, dtype, out]) Return the sum along diagonals of the array.
where(condition, [x, y], /) Return elements chosen from x or y depending on condition.
wrap_function_to_method(func) Wraps a function so that it calls the corresponding method on the Quantities object (if called with a Quantities object as the first argument).