Texas Instruments TI-80 User Manual - 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 The variables A through Z and q can hold only numbers- either decimals or fractions. You may store to these variables. The TI-80 can update X, Y, and T during graphing; therefore, you may wish to reserve those variables for graphing activities. The variables Lã through L6 are defined as lists. You cannot store another type of data to them. You can store any string of characters, functions, instructions, or variable names to the functions Yn (in FUNC mode) and Xnî and Ynî (in PARAM mode), by using either § or the Y= editor. The validity of the string is determined when the function is evaluated. The values of the Window variablesXMIN, XMAX, XSCL, @X, TSTEP, etc.must be real numbers. You may store to 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n, v, MINX, GX, a, r, REGEQ, X1, Y1, Q1, MED, Q3, etc.are reserved for use by the TI-80. You cannot store to them. A-26 Tables and Reference Information