Troubleshooting Tips

Tips for Notebooks

Executing a code cell gives an error

Code cells may depend on previous code cells. If a previous code cell has not been executed before, your current cell may lack required data. Try re-running all previous code cells in their given order

If you modified the code cell, look for hints at the end of the error message.

I have successfully executed all previous code cells in the given order but I still get an error message saying that some variable is undefined.

That may happen if you left the system idle for too long.

Your calculations run on a free virtual server provided by Depending on the load of the underlying server cluster, your server may be deleted if it is idle for too long. When you evaluate a cell after that, a new server is set up for you and you have to redo all required code cell executions.

The data in the text differ from the data in the code cells

The text analyzes a specific balloon flight which is loaded when the variable randomBalloon in the first cell has its default value of False. The text does not change when you change any code cell, for instance to load another flight.

In the web version, the Read button in the main menu shows the unchanged default version and you can reset all cells by reloading the page,

I don't see any interactivity

If you see a blue header, click on the Execute button in this header.

If, instead, you see a green button Open with one click, click on it to save your own copy as a Jupyter notebook in CoCalc. Note: You may have to create a paid CoCalc account to run notebooks with internet access.

I see only a part of the calculations.

Enlarge your window, use the scrollbars of the code cell or copy the code from the cell to another editor. Scrollbars may only appear after you click into the cell and move your mouse!

If you didn't change the code, you can see the full code in the web version when you select Read in the header menu.

Tips for Math Questions

Why should I do the Math questions?

Walk on safe ground! If you can answer the questions, you know you are ready to proceed. Even if you cannot, many questions have a Written Example that explains, how a similar problem is solved and what is the mathematical background.

You will notice, that the solution you provided for a linked question is used implemented in the next code cell. Thus, understanding the solution will help you to understand the code and to adapt it at will.

Do I have to use the mouse to enter a formula?
No, You can enter a formula right from your keyboard in a simple format called ASCIIMath. For example to enter \(\frac{x^2+3}{\sin(\sqrt{2})}\) you type (x^2+3)/sin(sqrt(2)).
Are the data in questions synchronized with the data in the code or text cells?

No, the questions provide similar problems.

I don't see a button to submit my answer.

It may be hidden behind the graphic formula editor; click anywhere eles to hide the editor.

If the question text is very long, you may need to scroll down.