# Revision history [back]

### Plot display problems when changing IP address?

The following senario has happened to me a couple of times when using Sage to demonstrate things in a classroom.

1. I'm working on a worksheet containing plots of simple functions for a calculus class in my office. The worksheet is on a notebook server somewhere (on campus, at sagenb.org, etc..).

2. I close my laptop, walk downstairs to class, open my laptop and plug into the projector. The laptop is now on a different wireless network, but still connects to the sage notebook server just fine. I get a red "searching for sage server" notice for just a second and then it disappears and the worksheet behaves like normal.

3. I'm half way through class, showing plots of this and that, and I decide that I want to change the bounds on one of my plots. Say I have

f(x) = 3x^4+4x^3-6*x^2 plot( f, (x,-2,3) )

and I want to zoom in and look at

plot( f, (x, -1, 1) )


and a new plot shows up, but it's not quite right. Sometimes I've had the experience that the plot doesn't change at all, I get the same plot as before (i.e. after editing the cell and hitting shift+enter again). Sometimes I get a new plot, but it's not correct. For example, this happened today and I got a new plot which was on the interval (-2, 1) not (-1, 1). I keep editing the cell and trying to re-evaluate the plot and get just continue to get incorrect domains or unchanged plots.

It seems like something is going on with cached images, or old images being re-displayed.

I finally figured out that I can solve the problem by cutting and pasting the code into a new cell, changing the name of the function to something different like h(x), and evaluating the cell.

Any thoughts on why this is happening or how I can prevent it from happening in the middle of class? Do I need to completely log out / log in to the server every time my IP address changes? Or maybe this problem is completely unrelated to the network change.

### Plot display problems when changing IP address?

The following senario has happened to me a couple of times when using Sage to demonstrate things in a classroom.

1. I'm working on a worksheet containing plots of simple functions for a calculus class in my office. The worksheet is on a notebook server somewhere (on campus, at sagenb.org, etc..).

2. I close my laptop, walk downstairs to class, open my laptop and plug into the projector. The laptop is now on a different wireless network, but still connects to the sage notebook server just fine. I get a red "searching for sage server" notice for just a second and then it disappears and the worksheet behaves like normal.

3. I'm half way through class, showing plots of this and that, and I decide that I want to change the bounds on one of my plots.

Say I have

f(x) = 3x^4+4x^3-6*x^2
3*x^4+4*x^3-6*x^2
plot( f, (x,-2,3) ) )


and I want to zoom in and look at

plot( f, (x, -1, 1) )


and a new plot shows up, but it's not quite right. Sometimes I've had the experience that the plot doesn't change at all, I get the same plot as before (i.e. after editing the cell and hitting shift+enter again). Sometimes I get a new plot, but it's not correct. For example, this happened today and I got a new plot which was on the interval (-2, 1) not (-1, 1). I keep editing the cell and trying to re-evaluate the plot and get just continue to get incorrect domains or unchanged plots.

It seems like something is going on with cached images, or old images being re-displayed.

I finally figured out that I can solve the problem by cutting and pasting the code into a new cell, changing the name of the function to something different like h(x), and evaluating the cell.

Any thoughts on why this is happening or how I can prevent it from happening in the middle of class? Do I need to completely log out / log in to the server every time my IP address changes? Or maybe this problem is completely unrelated to the network change.