Disallow or warn when ^ is used in answer fields

[mijenner]

Problem with ^ in answer fields

Formulas is THE best Moodle quiz question type for physics I've seen. Great work!

MathJax allows exponential notation to be written using hat notation by example x^2. However, this is not allowed in the answer fields were we are supposed to use double-star notation, e.g. x**2 or pow(x, 2), instead.

By mistake I used hat notation, and discovered that no warning is given. This is unfortunate as errors can go undetected.

Warn, disallow or translate

A warning, or directly disallowing hat notation in these fields would help the end user avoid doing mistakes.

It would be even better if ^ notation would be allowed, since it has become the defacto standard in LaTeX. If needed, ^ is translated internally to something useful for the underlying engine.

Kind regards, Michael

[PhilippImhof]

Thanks, Michael for reaching out. I cannot reproduce that problem. The ^ operator is allowed in answer types Numeric, Numerical formula and Algebraic formula, along with **. (There used to be an incorrect warning for that, but we fixed this in #108.) See the following screenshot:

Please note, however, that ^ will mean XOR on the teacher side, i. e. when entering the model answers. There is only one exception: inside model answers for the answer type Algebraic formula, which are always entered as strings and enclosed in quotes, ^ will mean exponentiation.

Can you please clarify the problem and confirm that you are using the latest version?

[mijenner]

We are using 5.3.3 for Moodle 3.9+ (2024042000).

I just ran into the problem again with Answer type = Numerical formula, trying to calculate rw^2 didn't work, changing it to rw**2 solved the issue.

[mijenner]

Note: I'm talking about what the teacher writes in the Answer* field.

[PhilippImhof]

But that's on the teacher side, no?

[mijenner]

Correct

[mijenner]

So to be clear: my request is a change on teacher side.

[PhilippImhof]

On the teacher side, ^ means XOR in every case except if you are using answer type "Algebraic formula". In that case, the answer is entered as a string, i. e. in quotes.

Changing this would break backwards compatibility for any question that actually uses XOR in the calculation of the model answer. (I personally do not use it, but I don't know if other people do.)

I understand your request and if I started Formulas question from scratch, I would not do that as it currently is. I am actually rewriting the core part (it's almost done) and there are several things where we will be stuck with legacy syntax due to decisions that were taken a long time ago.

However, I can imagine it would help to add some sort of warning when a teacher uses the ^ operator in their model answer, e.g. "Please note that ^ means XOR. If you want exponentiation, please use **." I could even add a button to auto-fix it.

What do you think about that?

[mijenner]

A warning is a lot better than nothing, it would be a great addition.

Where can the warning be displayed? Next to the Answer* field is obvious, but when saving a question we are led to the top and if nothing is displayed there it may go unnoticed?

By the way, what other boolean operators are available?

[mijenner]

Found the other operators here: https://dynamiccourseware.org/course/view.php?id=100&section=1

[PhilippImhof]

Where can the warning be displayed? Next to the Answer* field is obvious,

The warning would be displayed below the field while the user is typing.

but when saving a question we are led to the top and if nothing is displayed there it may go unnoticed?

If there are validation errors, the form is automatically scrolled to a position where the error message is visible. In this case, however, that would not be a validation error, but only a warning generated via Javascript. Otherwise, the form would always fail validation with a ^ in the model answer and thus that operation could not be used anymore. (AFAICS, Moodle's Form API does not support warnings, it only supports errors.)

[mijenner]

While typing is a great moment!