This is a doenet problem inside of a pretext book hosted on Runestone, and one student is getting this error and can’t view or complete the problem. Everyone else seems to be okay, and I have no idea what this means or what the issue is.
The source for the exercise is here.
It appears to be broken for that student because there is a flaw in restoring the state after the point P has been dragged. It should affect any student after they drag the point and then attempt to reload with their saved state.
Created a bug report.
Until we have a fix, a workaround is to explicitly include the coordinates in the definition of the point P, e.g.,
<point name="P" labelIsName labelPosition="lowerRight">
(0,0)
<constrainTo>$f</constrainTo>
</point>
The bug is restricted to the case where the coordinates are not specified.
Thank you for the quick diagnosis! In that case, I’m surprised more students didn’t encounter the error. Maybe they completed it in one attempt? Or didn’t drag the point?
Right, the must have not reloaded.
Fix is in the newest release we just made.