Technical Support

The following are guidelines to help solve any problems you may have using this web site. If you cannot find the answer you need please send us your question and we will endeavor to answer it as quickly as possible.

Print button has vanished from the applets

They were removed in December 2019. As new devices like tablets and phones had to be supported, the print button on the applets became both difficult to implement and increasingly irrelevant. The best way to get a snapshot of the applet at any given time is the use a screen capture utility - which is built in to most operating systems. The advantage of doing it this way is that you get an image captured which can be printed or pased into any application.

For a summary of ways to do this see How to capture parts of the screen on this site.

Calculus Pages - no animations displayed.

The calculus pages are written in Java, but the rest are in HTML5 (JavaScript). If you are having problems with the calculus pages, see the Calculus section at the bottom of this page.

No animations displayed

If no animations are displayed on non-calculus pages:

  1. Old browsers

    The most common reason for this is that the browser is very old. The animations are written in HTML5, which was built into all current browsers a few years ago. Some older browsers however are still in use, and are no longer being updated. A common case is the Internet Explorer browser (IE) on Windows XP machines. There is no version of IE that runs on XP that supports HTML5. The solution is to install either Firefox browser or the Google Chrome browser (recommended).

    You can download Chrome from the Google site.

  2. Is Javascript enabled?

    The symptom of this is a blank animation window.

    Javascript is a language that runs inside the browser. It is used on this site to run the animations and so must not be turned off. In the settings of the browser is a checkbox to enable or disable Javascript. It must be enabled. To find this setting in your browser, do a Google search "disable JavaScript" and the browser name. These setting panels change all the time with each version so cannot be documented here. In some browsers it is labelled "Enable scripting".

The calculus pages have no animations

The calculus applets are written in Java, so the most likely cause is that the Java browser plugin is missing or disabled. There is a Java control panel that has the settings for this.

You can download Java from the Java site.

The calculus pages keep asking for a security confirmation before loading the Java animations.

The calculus applets are now the only applets on the site written in Java. With each release of the Java plug-ins, they have become more and more paranoid about security, to the point now where they ask for your OK every single time you load an applet.


  1. First download the latest Java plug in. Version 7 update 51 or later is needed.
  2. Go to the Java control panel. Select the security tab
  3. At the bottom is a site exception list. Add to the list ""
The next time you go to a calculus page it will ask you one time to confirm, then never again for this site.

Other pages about this site