Python - math.sin() method example

math.sin is a method that takes only one parameter and returns an approximation of sine mathematical function.

import math

print(math.sin(0))                    # 0   <-     0 degrees
print(math.sin(1.5707963267948966))   # ~1  <-   ~90 degrees ==  pi / 2
print(math.sin(3.1415926535897932))   # ~0  <-  ~180 degrees ==  pi
print(math.sin(4.71238898038469))     # ~-1 <-  ~270 degrees == -pi * (3/2)
print(math.sin(6.2831853071795850))   # ~0  <-  ~360 degrees ==  pi * 2

print(math.sin(-1.5707963267948966))  # ~-1 <-  ~-90 degrees == -pi / 2

Note: 1.2246467991473532e-16 and -1.133107779529596e-15 should be equal to 0 but they are not because of compuptation precision error.

1. Documentation

math.sin(x)

2. Working with radians

import math

x1 = 0.0            # beginning of calculation in radians
x2 = math.pi / 2    # ending of calculation radians

dx = math.pi / 9    # calculation step in degrees

rad = x1
while rad <= x2:
    y = math.sin(rad)
    print("sin(", rad, "rad ) =", y)
    rad += dx

Output: 

sin(0 rad) = 0
sin(0.3490658503988659 rad) = 0.3420201433256687
sin(0.6981317007977318 rad) = 0.6427876096865393
sin(1.0471975511965976 rad) = 0.8660254037844386
sin(1.3962634015954636 rad) = 0.984807753012208

3. Working with degrees

import math


def calculate_sin(deg):
    radians = (math.pi / 180) * deg
    return math.sin(radians)


# Example:
x1 = 0.0   # beginning of calculation in degrees
x2 = 90.0  # ending of calculation degrees

dx = 15.0  # calculation step in degrees

deg = x1
while deg <= x2:
    y = calculate_sin(deg)
    print("sin(", deg, " deg) = ", y)
    deg += dx

Output: 

sin(0 deg) = 0
sin(15 deg) = 0.25881904510252074
sin(30 deg) = 0.49999999999999994
sin(45 deg) = 0.7071067811865476
sin(60 deg) = 0.8660254037844386
sin(75 deg) = 0.9659258262890683
sin(90 deg) = 1

4. Reversed console plot example

import math

x1 = 0.0       # beginning of sine chart
x2 = 2 * 3.14  # end of sine chart

dx = 3.14 / 4.0  # x axis step
dy = 1.0 / 5.0   # y axis step

rad = x1
while rad < x2:
    y1 = 0.0
    y2 = math.sin(rad) + 1
    line = ""

    y = y1
    while y < y2:
        line += " "
        y += dy

    print(line, "+")
    rad += dx

Output: 

      +
          +
           +
          +
       +
   +
  +
   +

References

1. Sine - Wikipedia