H. 8:Test
The TI89 will compare two values using one of the relational operators shown in the figure below. The calculator will return a value of true or false. The values can be real or complex numbers, expressions, or lists. The operators can be used in programs to control the flow of a program. One of the uses that students in algebra, trigonometry, or calculus will find useful is with piecewise defined graphs.
Press
.
Use
and
to select the menu of choice. 
Not all options are given in the entry format. Options that are used frequently will be included, but others are omitted from the table. For a complete format listing, you can check the TI89 manual. Results in complex mode are not covered. They can be found in the manual.
Some of these operations can be accessed using the and keys.
For <, press . For , press . For >,press . For , press .
Operation

Entry Format

Explanation

Screen

1:>, 2:<, 3:, 4:, 5:=, 6: 
expression1 = expression2 
Returns true if expression1=expression2. Returns false if expression 1 is determined to not be equal to expression2. Anything else returns a simplified form of the equation. For lists and matrices, returns comparisons element by element. 

7:not  not Boolean expression1  Returns true, false,
or a simplified Boolean expression1. 

8:and  Boolean expression1
and expression2 Boolean list1 and list2 Boolean matrix1 and matrix2 
Returns true or false
or a simplified form of the original entry. 

9:or 
Boolean expression1 or 
Returns true or false
or a simplified form of the original entry. Returns true if either or both expressions simplify to true. Returns false only if both expressions evaluate to false. 

A:xor  Boolean expression1
xor Boolean expression2 
Returns true if Boolean
expression1 is true and Boolean expression2 is false, or vice versa. Returns false if Boolean expression 1 and Boolean expression2 are both true or both false. 

B:isPrime  isPrime(number)  Returns true or false
to indicate if number is prime. 