A student sent me a file with obviously wrong unit handling by SMath Studio. A variable was not stored in the units as specified. I don't know how he could make this (was made on a french computer environment (keyboard, OS language)

mwe.sm (3 KiB) downloaded 52 time(s).
Display in 8253

Display in 6884 (the oldest on my computer)


The upper definition is from the worksheet of the student, the lower was typed by me.
When copying the cells to an editor, the hex representations look the same.

What could have gone wrong?

Meanwhile I found the culprit. The student (by chance or deliberately) has set the option "Ignore units" which I never use and therefore did not think of at first glance.

Yet in between version 6884 and 8253 a bug must have been introduced. It makes a definition from a cell with activated "ignore units" neither being stored with the specified unit (as if the option wasn't set), nor without unit (as would be expected). Instead, SMath Studio stores part of the definition (or something random, who knows), so creating perfect confusion and making the teacher look stupid by recommending such programs.

I consider this being a bug and I also would add to the survival rules: Never use "Ignore units" feature.

This is mainly due to the fact that there is no visible clue that this feature is activated in a definition. I'd recommend something like displaying ignored units in a definition in gray.