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Python Programming/Math

< Python Programming

For basic math including addition, subtraction, multiplication and the like, see Basic Math and Operators chapters. For quick reference, the built-in Python math operators include addition (+), subtraction (-), multiplication (*), division (/), floor division (//), modulo (%), and exponentiation (**). The built-in Python math functions include rounding (round()), absolute value (abs()), minimum (min()), maximum (max()), division with a remainder (divmod()), and exponentiation (pow()). Sign function can be created as "sign = lambda n: 1 if n > 0 else -1 if n < 0 else 0".

Math edit

A range of mathematical functions is available from math module of the standard library: 

import math

v1 = math.sin(10)       # sine
v2 = math.cos(10)       # cosine
v3 = math.tan(10)       # tangent 

v4 = math.asin(10)      # arc sine
v5 = math.acos(10)      # arc cosine
v6 = math.atan(10)      # arc tangent

v7 = math.sinh(10)      # hyperbolic sine    
v8 = math.cosh(10)      # hyperbolic cosine
v9 = math.tanh(10)      # hyperbolic tangent

vA = math.pow(2, 4)     # 2 raised to 4
vB = math.exp(4)        # e ^ 4
vC = math.sqrt(10)      # square root
vD = math.pow(5, 1/3.0) # cubic root of 5
vE = math.log(3)        # ln; natural logarithm
vF = math.log(100, 10)  # base 10

vG = math.ceil(2.3)     # ceiling
vH = math.floor(2.7)    # floor

vI = math.pi
vJ = math.e

Example code using in-built operators edit

This code was made to replicate the log function in a calculator

import time
base_number = input("[A]input base number: ")
new_number = 0
result = input("[end number]input result ")
exponent = 0

while int(new_number) != int(result):
    exponent += float("0.0000001")
    new_number = int(base_number)**float(exponent)
    print(new_number)
    
else:
    print("")
    print("The exponent or X is " + str(exponent))
    time.sleep(200)

Cmath edit

The cmath module provides similar functions like the math module but for complex numbers, and then some.

Random edit

Pseudo-random generators are available from the random module: 

import random
v1 = random.random()     # Uniformly distributed random float >= 0.0 and < 1.0.
v2 = random.random()*10  # Uniformly distributed random float >= 0.0 and < 10.0
v3 = random.randint(0,9) # Uniformly distributed random int >= 0 and <=9
li=[1, 2, 3]; random.shuffle(li); print(li) # Randomly shuffled list

Decimal edit

The decimal module enables decimal floating point arithmethic, avoiding certain artifacts of the usual underlying binary representation of floating point numbers that are unintuitive to humans. 

import decimal
plainFloat = 1/3.0
v1 = plainFloat # 0.3333333333333333
decFloat = decimal.Decimal("0.33333333333333333333333333333333333333")
v2 = decFloat   # Decimal('0.33333333333333333333333333333333333333')
decFloat2 = decimal.Decimal(plainFloat)
v3 = decFloat2  # Decimal('0.333333333333333314829616256247390992939472198486328125')

Fractions edit

The fractions module provides fraction arithmetic via Fraction class. Compared to floating point numbers representing fractions, Fraction fractions do not lose precision. 

from fractions import Fraction
oneThird = Fraction(1, 3)
floatOneThird = 1/3.0
v1 = Fraction(0.25)                  # 1/4
v2 = Fraction(floatOneThird)         # 6004799503160661/18014398509481984
v3 = Fraction(1, 3) * Fraction(2, 5) # 2/15

Statistics edit

The statistics module, available since Python 3.4, provides some basic statistical functions. It only provides basics; it does not replace full-fledged 3rd party libraries such as numpy. For Python 2.7, the statistics module can be installed from pypi. 

import statistics as stats
v1 = stats.mean([1, 2, 3, 100]) # 26.5
v2 = stats.median([1, 2, 3, 100]) # 2.5
v3 = stats.mode([1, 1, 2, 3]) # 1
v4 = stats.pstdev([1, 1, 2, 3]) # 0.82915...; population standard deviation
v5 = stats.pvariance([1, 1, 2, 3]) # 0.6875; population variance

External links edit

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