Texas Instruments PLUS TI-89 - Manual (Page 64)

Chapter 2: Operating the Calculator 47
02OPER DOC TI-89/TI-92 Plus: Operating the TI-89/TI-92 Plus (English) Susan Gullord Revised: 02/23/01 1:06 PM Printed: 02/23/01 2:11 PM Page 47 of 44
A variable name:
¦ Can use 1 to 8 characters consisting of letters and digits. This
includes Greek letters (but not
p), accented letters, and
international letters. Do not include spaces.
−
The first character cannot be a digit.
¦ Can use uppercase or lowercase letters. The names AB22 , Ab22 ,
aB22 , and ab22 all refer to the same variable.
¦ Cannot be the same as a name that is preassigned by the
TI -89 / TI-92 Plus . Preassigned names include:
−
Built-in functions (such as abs ) and instructions (such as
LineVert ). Refer to Appendix A.
−
System variables (such as xmin and xmax , which are used to
store graph-related values). Refer to Appendix B for a list.
Variable Description
myvar OK
a OK
Log Not OK, name is preassigned to the log function.
Log1 OK
3rdTotal Not OK, starts with a digit.
circumfer Not OK, more than 8 characters.
You can save any TI -89 / TI-92 Plus data type as a variable. For a list of
data types, refer to getType() in Appendix A. Some examples are:
Data Types Examples
Expressions 2.54, 1.25 í 6, 2 p , xmin/10, 2+3 i , (x м 2) с , 2/2
Lists {2 4 6 8}, {1 1 2}
Matrices [1 0 0] ,  
1 0 0
3 4 6
Character strings “Hello”, “The answer is:”, “xmin/10”
Pictures
Functions myfunc(arg), ellipse(x,y,r1,r2)
Storing and Recalling Variable Values
When you store a value, you store it as a named variable. You
can then use the name instead of the value in expressions.
When the
TI - 89 / TI - 92 Plus encounters the name in an
expression, it substitutes the variable’s stored value.
Rules for Variable
Names
Examples
Data Types