Texas Instruments TI-80 Manual Book page 210

TI-80 Variables
The variables listed below are used by the TI-80 in various ways. Some have
restrictions on their use.
User Variables
System
Variables
A-26 Tables and Reference Information
The variables A through
either decimals or fractions. You may store to these variables.
The TI-80 can update
you may wish to reserve those variables for graphing
activities.
The variables Lã through
store another type of data to them.
You can store any string of characters, functions, instructions,
or variable names to the functions
X n î and Y n î (in PARAM
Y= editor. The validity of the string is determined when the
function is evaluated.
The values of the Window variables
@X , etc. must be real numbers. You may store to
TSTEP,
them. Since the TI-80 can update some of them, as the result
of a Zoom instruction, for example, you may wish to reserve
these variables for graphing activities.
The statistical result variables
X1 , Y1 , Q1 , MED , Q3
You cannot store to them.
q
Z and can hold only numbers—
X , Y , and T during graphing; therefore,
L6 are defined as lists. You cannot
Y n (in
mode), by using either § or the
XMIN
v
n , , MINX
, etc. are reserved for use by the TI-80.
FUNC mode) and
, , ,
XMAX XSCL
GX
, , a , r , REGEQ ,