Texas Instruments PLUS TI-89 - Manual (Page 311)

294 Chapter 17: Programming
17PROGRM.DOC TI-89/TI-92 Plus: Programming (English) Susan Gullord Revised: 02/23/01 1:14 PM Printed: 02/23/01 2:18 PM Page 294 of 40
¦ Type the operator directly from the keyboard.
— or —
¦ Press 2 I and select
8:Test . Then select the
operator from the menu.
— or —
¦ Display the built-in functions.
Press:
TI . 89: ½
TI . 92 Plus: 2 ½
The test operators are listed
near the bottom of the
„
Built-in menu.
Relational operators let you define a conditional test that compares
two values. The values can be numbers, expressions, lists, or
matrices (but they must match in type and dimension).
Operator True if: Example
> Greater than a>8
< Less than a<0
‚ Greater than or equal to a+b ‚ 100
 Less than or equal to a+6  b+1
= Equal list1=list2
ƒ Not equal to mat1 ƒ mat2
Boolean operators let you combine the results of two separate tests.
Operator True if: Example
and Both tests are true a>0 and a  10
or At least one test is true a  0 or b+c>10
xor One test is true and the
other is false a+6<b+1 xor c<d
The not function changes the result of a test from true to false and
vice versa. For example:
not x>2 is true if x  2
false if x>2
Note: If you use not from the Home screen, it is shown as ~ in the
history area. For example, not x>2 is shown as ~(x>2) .
Conditional Tests
Conditional tests let programs make decisions. For example,
depending on whether a test is true or false, a program can
decide which of two actions to perform. Conditional tests are
used with control structures such as If...EndIf and loops such
as While...EndWhile (described later in this chapter).
Entering a Test
Operator
Relational Tests
Tip: From the keyboard,
you can type:
>= for
‚
<= for 
/= for ƒ
(To get the / character,
press
e .)
Boolean Tests
The Not Function