In addition to running the configuration assistant, you can enable or disable certain classes of expressions using the Expression Types dialog. Disabling expression types you don't use will help improve the accuracy of your results.
To enable or disable individual expression types:
Choose Expression Types from the Math menu to display the Expression Types dialog.
For each expression type in the scrolling list, decide whether you want to enable it or disable it. A brief description of each item appears just below the list to help you choose.
Be sure any expression types you expect to use are checked. Remove the check marks from any types you don't plan to use.
Tap OK to save your changes.
If you later find that you need a particular expression type, you can reenable it at any time.