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SciPy constants package provides a wide range of constants, which are used in the general scientific area.
SciPy Constants Package
The scipy.constants package provides various constants. We have to import the required constant and use them as per the requirement. Let us see how these constant variables are imported and used.
To start with, let us compare the ‘pi’ value by considering the following example.
#Import pi constant from both the packages
from scipy.constants import pi
from math import pi
print("sciPy - pi = %.16f"%scipy.constants.pi)
print("math - pi = %.16f"%math.pi)
The above program will generate the following output.
sciPy - pi = 3.1415926535897931 math - pi = 3.1415926535897931
List of Constants Available
The following tables describe in brief the various constants.
Mathematical Constants
| Sr. No. | Constant | Description |
|---|---|---|
| 1 | pi | pi |
| 2 | golden | Golden Ratio |
Physical Constants
The following table lists the most commonly used physical constants.
| Sr. No. | Constant & Description |
|---|---|
| 1 |
c Speed of light in vacuum |
| 2 |
speed_of_light Speed of light in vacuum |
| 3 |
h Planck constant |
| 4 |
Planck Planck constant h |
| 5 |
G Newton’s gravitational constant |
| 6 |
e Elementary charge |
| 7 |
R Molar gas constant |
| 8 |
Avogadro Avogadro constant |
| 9 |
k Boltzmann constant |
| 10 |
electron_mass(OR) m_e Electronic mass |
| 11 |
proton_mass (OR) m_p Proton mass |
| 12 |
neutron_mass(OR)m_n Neutron mass |
Units
The following table has the list of SI units.
| Sr. No. | Unit | Value |
|---|---|---|
| 1 | milli | 0.001 |
| 2 | micro | 1e-06 |
| 3 | kilo | 1000 |
These units range from yotta, zetta, exa, peta, tera ……kilo, hector, …nano, pico, … to zepto.
Other Important Constants
The following table lists other important constants used in SciPy.
| Sr. No. | Unit | Value |
|---|---|---|
| 1 | gram | 0.001 kg |
| 2 | atomic mass | Atomic mass constant |
| 3 | degree | Degree in radians |
| 4 | minute | One minute in seconds |
| 5 | day | One day in seconds |
| 6 | inch | One inch in meters |
| 7 | micron | One micron in meters |
| 8 | light_year | One light-year in meters |
| 9 | atm | Standard atmosphere in pascals |
| 10 | acre | One acre in square meters |
| 11 | liter | One liter in cubic meters |
| 12 | gallon | One gallon in cubic meters |
| 13 | kmh | Kilometers per hour in meters per seconds |
| 14 | degree_Fahrenheit | One Fahrenheit in kelvins |
| 15 | eV | One electron volt in joules |
| 16 | hp | One horsepower in watts |
| 17 | dyn | One dyne in newtons |
| 18 | lambda2nu | Convert wavelength to optical frequency |
Remembering all of these are a bit tough. The easy way to get which key is for which function is with the scipy.constants.find() method. Let us consider the following example.
import scipy.constants res = scipy.constants.physical_constants["alpha particle mass"] print res
The above program will generate the following output.
[ ''alpha particle mass'', ''alpha particle mass energy equivalent'', ''alpha particle mass energy equivalent in MeV'', ''alpha particle mass in u'', ''electron to alpha particle mass ratio'' ]
This method returns the list of keys, else nothing if the keyword does not match.
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