SciPy - Constants

In scientific and mathematical calculations, universal constants such as π (pi) or the gravitational constant G are frequently needed. Whether it's determining the area of a circle or calculating gravitational force, having reliable constants readily available helps streamline the process.

Scipy.constants module in SciPy allows users to access collection of mathematical, physical and unit conversion constants effortlessly with a single line of code.

Accessing Constants

Constants can be accessed using the format:

scipy.constants.CONSTANT_NAME

Below listed constants are commonly used:

import scipy.constants as const

print("Pi:", const.pi)
print("Golden ratio:", const.golden_ratio)
print("Speed of light:", const.c)
print("Gravitational constant:", const.G)
print("Gas constant (R):", const.R)
print("Boltzmann constant:", const.k)
print("Proton mass:", const.proton_mass)

Output

Finding Constants

Use the find() method to search for constants by keyword.

import scipy
res = scipy.constants.find("electron")
print(res, end='\n')

Output

Physical Constants: Value, Unit and Uncertainty

Not only the value but also the corresponding unit and the degree of uncertainty of a physical constant can be retrieved using physical_constants dictionary from scipy.constants.

scipy.constants.physical_constants['name']

import scipy.constants as const
# This return a tuple(vslue, unit, uncertainty)
print(const.physical_constants['alpha particle mass'])

Output

(6.644657345e-27, 'kg', 2.1e-36)

Example: Sample Use Cases

import scipy.constants as const

# Area of a circle using pi
def area_of_circle(r):
    return const.pi * r * r

# Gravitational force
def force_gravity(M, m, dist):
    return (const.G * M * m) / (dist ** 2)

print("Area of Circle:", area_of_circle(5))
print("Gravitational Force:", force_gravity(10, 5, 1))

Output

Commonly Used Constants in SciPy

Unit Conversion Constants

Mass Units:

Time Units:

Length Units:

Pressure Units:

Area Units:

Speed Units:

Related Articles:

• SciPy Integration
• Special Functions in SciPy
• Setup of SciPy in PyCharm
• Difference between NumPy and SciPy