Week 2: Closure

Syllabus

• Concept of statement illustrated by the print statement and assignment statement

• Assignments and assignment operator = (formal definition)

• The concept of expressions

• Variables and types (formal definition)

• Valid variable names and naming conventions

• The type() function

• Concept of namespace (an informal definition)

• Reassignments

• Augmented assignments: += , -= , *= , /= , etc.

• Numeric data types: int , float

• String data type, str with single or double quote

• String operators + (concatenation) and * (repetition)

• The len() function for strings

• Type casting with int() , float() , str()

• Numeric operators: % (modulus) and // (floor division)

• Built-in-functions with multiple arguments: max() , min() , and print()

• The math module

• By example, the keyword import and the import statement

• Functions from the math module: math.sin() , math.cos() , math.sqrt() , math.exp() , math.log() , math.ceil() , math.floor() .

• Constant math.pi

• Boolean data type and bool()

• Comparison operators: == , != , < , > , <= , >=

• Logical operators: and , or , not

• Good practice, e.g. avoid print = 6

• Understanding error messages

Checkpoint

Checkpoint 2.1: Road angle

In cycling, a road gradient of 5% means that for every 100 meters traveled horizontally, you climb 5 meters vertically.

Let \(g\) be the gradient in percent. The road angle \(\alpha\) satisfies

\[ \tan\alpha = \frac{g}{100} \]

Write a Python script road_angle.py where you initialize a variable g for the road gradient (in percent), calculate the road angle in degrees, and print the angle.

Checkpoint 2.2: Elapsed time

A time interval is measured in seconds. You want to convert this to days, hours, minutes, and seconds.

Write a Python script elapsed_time.py where you initialize a variable seconds for the time interval in seconds, calculate the equivalent number of days, hours, minutes, and seconds, and print the result.