# Option to turn on / off arrowheads at the end of lines

Lego shared this idea 10 years ago

Hi all,

Currently, when you graph function (eg. y = 2x + 3), the graph does not have arrowheads at either end. It would be great if a feature could be included so users have the option to turn it on and off as they wish.

Let me know if you are experiencing the same thing.

-Lego-

1

Something similar has been requested about the axes. But consider this on your request, that this feature would have to able to automatically turn of when the domain/range is limited. Secondly, it would require the arrowheads to move whenever you need to zoom/scroll the screen. This is easier with the axes, but much more difficult with functions in general.

This is a good idea, but consider the difficulty of creating an algorithm that will always work. I have not seen this feature with other tools. Do you have an example tool that does this? If you do, could you post a link, I would like to see it.

Thanks,

Tony

1

y = 2x + 3 has no ends! It's an infinite straight line.

1

I believe Lego understands that this is so; however, here in the US there are some instructors that want to see the arrowhead on the visible ends of a graph.

Tony

1

Hi

I'm not a fan of the arrow head on graphs either, especially if they were to appear on the ends of straight lines. It would surely create confusion with vectors for some students.

regards

Paul

1

hello

what about f(x) = cbrt(40 x²) - 8 or 10 atan(1/x) in standar view.

the student may think that there vertical asymptotes in x=0.

saludos

1

I am not really a fan of the arrowheads myself in that a zoom can show that they continue infinitely.

Although, these two equations are examples where Extremum[f,-0.1,0.1] does not work. This is probably because f(x) is not a polynomial equation.

The Function Inspector does display information on the extremes. I am not sure if I can rely on these extremes. Does Inspector have an limitations on the type of functions.

Tony

1

Hi, Extremum needs the function to be continuous on the given interval (not necessarily a polynomial).

Function inspector uses GeoGebra commands like Extremum or Root internally, so the limitations there are the same.

1

hello

extremum does not work for me if the function is not differentiable

A = Extremum[abs(x), -1, 1] is undefined

saludos

1

I'm not a programmer, so I'm unsure of the technical difficulties, but thanks for pointing it out to me!

As for why we use the arrowheads... I'm a teacher from Sydney, we encourage students to use arrowheads on the end of lines to indicate that the lines extend on both ends (if it does).

For lines that are bounded on one or both ends, we encourage the use of a filled-in circles if the end point(s) are included as part of the graph, empty circle(s) otherwise. Much like what you do when graphing linear inequalities.

And so, when I design my worksheets, I have to manually insert the arrowheads afterwards, that's why I asked to see if this feature was possible...

I did come across this program, which seems to be giving arrowheads at the end of graphs, as well as plotting the asymptotes (automatically?)... http://www.efofex.com/fxgraph.php