Texas Instruments TI86 User Manual - Page 90

78 Chapter 5: Function Graphing You can edit expressions you inserted using Rcl. Notes about Defining Function Equations ♦ You can include functions, variables, constants, matrices, matrix elements, vectors, vector elements, lists, list elements, complex values, or other equations in the equation. ♦ If you include matrices, vectors, or complex values, the equation must evaluate to a real number at each point. ♦ You can include another defined function in an equation. For example, given y1=sin x and y2=4+y1, the function y2 would equal 4 plus the sine of x. ♦ To enter a function name, select y from the equation editor menu, and then enter the appropriate number. ♦ To insert the contents of an equation variable, use RCL (Chapter 1). To enter the equation variable at the Rcl prompt, use the ALPHA keys, alpha keys, and other character keys. ♦ To select all functions from the home screen or in the program editor, select FnOn from the CATALOG (or enter the individual characters) and press b. ♦ To select specific functions from the home screen or in the program editor, select FnOn from the CATALOG (or enter the individual characters), enter the number of each function, and press b. For example, to select y1, y3, and y5, enter FnOn 1,3,5. ♦ To deselect functions from the home screen or in the program editor, use FnOff the same way you use FnOn to select functions. ♦ When a function evaluates to a non-real number, the value is not plotted on the graph; no error is returned.