Texas Instruments TI-89 Titanium User Manual page 242

• Infinite recursions can occur when you define a substitution variable in terms of
itself.
sin(x)|x=x+1
When you enter a substitution that causes an infinite recursion:
- An error message is displayed.
When you press N, an error is
-
shown in the history area.
• Internally, an expression is sorted according to the automatic simplification rules.
Therefore, products and sums may not match the order in which you entered them.
- As a general rule, you should
substitute for a single variable.
Symbolic Manipulation
Substitutes sin(x+1), sin(x+1+1),
sin(x+1+1+1), etc
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