Strange behaviour of function zero points

Both the file you have created here and the one in the screenshot have quite odd parameters in the Roots command, since you set as start and end point the same value.

e.g. Roots(f, 0.4, 0.5) works fine.

What I don't understand is that reopening your file on v.6 the guess interval for roots changes.

For example I now have this

Recreating your file from scratch doesn't have any problem, even when zooming in a lot.

But I've used (0.4, 0.5) as guess interval for the roots.

Also with a wider decimal approximation, I have no issues. See the attached file.

I think that the problem in your file is that you set the guess interval for the roots as a single point, instead of an interval.

Anyway, I'm looping this post to the devs, so they can have a look at it.

I see it now.

I missed the fact that you used "Special points"option to get the roots.

In this case, zooming changes automatically the guess interval for roots. All the points are recalculated at every zoom action.

Thanks, we'll check if we can improve this

Just a heads up, this may be more involved. I created the attached file by typing in function f, selecting "extreme points" and "zero points" from the menu above, and using the f' and f'' typed in command to create those graphs and did the same point operations on them from the button menu above.

Now, whenever you click a graphed function off and on again via its color point, geogebra will add a new set of points for extreme and zero for that function, no matter f, f' or f''.

This example does not involve zooming, so I suspect the cause of both problems is in some call to "extreme points" or "zero points" whenever a function is redrawn, either by switching it on and off, or by zooming.

This would also explain why Simona could not reproduce the problem at first - an experienced user well versed in geogebra will probably type in commands they know by heart instead of using the menu.

Then again, I am not a programmer, so this is just a hunch. ;)