Sicalc

Some tools to make physic class easier by handling the SI Units.

Installation

The installation works simply via pip:

pip install sicalc

Usage

Simply import the units you need and calculate with them! A number (float/int) will be associated with the unit by multiplication giving an instance of ValueWithUnit. By the multiplication of two of those instances we get a new ValueWithUnit-instance which keeps track of the multiplied units.

from sicalc.units import m, s
velocity = 20_000 * m / s
t = 60*s
distance = velocity * t
print(distance) # --> <1.20000E+06, m>

The common unit prefixes are defined aswell.

from sicalc.units import m, s, kilo
km = kilo*m
velocity = 20 * km / s
t = 60*s
distance = velocity * t
print(distance) # --> <1.20000E+06, m>

Most constants are defined by the package too:

from sicalc.units import s
from sicalc.constants import c
print(5*s*c)

When adding two values, make sure those are of the same unit.

from sicalc.units import m, s, kg, N
F1 = 5*N
F2 = kg*m/s**2
P = kg*m/s
F = F1 + F2 # correct
F + P # wrong, will give an Exception :(

Using functions like math.sqrt wont work. Therefor common functions are provided in sicalc.func. Note that these functions check unit behaviour too:

from sicalc.units import m
from sicalc.func import sqrt, ln
d1 = 2*m
d2 = 3*m

# will work
print(ln(d1/d2)) # --> The parameter of ln must not have a unit
print(sqrt(d1*d2)) # --> The parameter of sqrt requires, that all power of units are dividable by 2, e.g. m**2, m**4, kg*kg/(s*s)

# wont work
print(ln(d1)) # --> ln cant handle a unit
print(sqrt(d1)) # --> What should be the square-root of the unit "meter"??

numpy support

Numpy arrays seem to work as values too. Note that not all functions are tested yet.

from sicalc.units import m, s
import numpy as np
d = np.array([1, 2, 3])*m
t = np.array([4, 5, 6])*s
v = d/t
print(v)
# Output: [<250.00000E-03, m^1*s^-1> <400.00000E-03, m^1*s^-1>
 <500.00000E-03, m^1*s^-1>]