An Introduction to Matrix Computations in Python: Just the basics

A variable is like a container that can be used to store information or data. In Python you assign a value to a variable using = .

Run the Python code below by clicking the Evaluate (Python) button.

Note that the function print() was needed to display the value of the variable.

For example, the following code has a syntax error. Run the code as is and see what happens.

Python recognizes simple arithmetic symbols like + -, *, /.

Meanwhile a hashtag # can be used to tell Python to ignore code, reading what follows as a comment by the author rather than a Python command.

Comments can help anyone reading your code understand what that section of the code is doing. You can also comment out portions of code to isolate a bug.

Just like in math, variables can be helpful when the information will change. Recall the formula for the area of a circle \(A=\pi r^2\text{.}\)

In the code below,

Note that print will display comma separted items one right after the other. In the code above we first displayed the string “The area of a circle is” followed by the current value of our variable circle_area.

One error we can make when creating and editing code is to mis-type a command causing Python to not understand the syntax, that is the chosen command, in our program. Another error is when we make our meaning unclear, more of a semantic issue. For example you can add numbers to numbers or strings of letters to strings of letters in Python but if we try to add a number to a string of letters, Python will not know what is meant by adding.