Lesson 5- Input and Output: Working With Math Formulas
Learning Goals:
- To know about some of the more common math formulas provided by Python
- To know about some math constants in Python
- To be able to translate a formula from math into a formula in Python code
-
The math library
In this lesson, you will be making use of the math library. In the first line of code you need an import statement, namely: import math
There are a number of math functions that are part of the math library. A few key functions are:
| Function Name |
Purpose /notes |
| math.pow(p, q) |
Returns pq (floating point) |
| math.trunc(p) |
Where p is floating point, it returns the integer part (decimal is discarded) |
| math.floor(p) |
Where p is floating point, it rounds to the next lowest integer |
| math.ceil(p) |
Where p is floating point,it rounds to the next higher integer |
| math.sqrt(p) |
Returns the square root of p (floating point) |
What follows are some useful stored constants in Python. Use them in place of numbers. Constants do not make use of brackets and are treated like variables.
| Constant |
Value |
| math.PI |
3.141592653589793 (the value of π) |
| math.e |
2.718281828459045 (the value of Euler's constant) |
| math.inf |
Positive infinity, ∞ |
What to do:
- Predict. Look at the code below in the green box. In your reflection, predict what output you would expect from the statement.
import math
length = input("Please input a length: ")
area = math.pow(length, 2)
print("The area of a square of side length", length, "is:", area)
- Run. Run the code in pyCharm, to check your response.
- Inspect. State the behaviour of this code. When it stopped execution, why did it stop? What did you input? Did the output match what you did on your calculator?
- Modify/Make. This time, compute the area of a square with a semicircle on one side, in the shape of a Norman Window. The area of the semicircle is 0.5*πr2; while the area of the square can be (2r)2=4r2. The total area is the sum of these: 0.5*πr2 + 4r2. In your reflection, state the reason why r has to be multiplied by 2 in part of the formula. In the diagram below, x = y.
Sample session:
Area of a Norman Window shape
Input the circle's radius: 5
Area is: 139.26990816987242