# SLOPEFIE for the Texas Instruments TI 82:

SLOPEFIE sketches a field of sample slopes for solutions of , where g is any reasonably well-behaved function.

To enter the program, select 'PRGM', 'NEW'. When 'Name =' appears, type in 'SLOPEFIE',then press the 'ENTER' key. When you have finished typing in the program, press '2^{nd}QUIT'. To run the program, select 'PGRM', 'EXEC', with 'SLOPEFIE' highlighted.

PLEASE NOTE: 'FnOff', 'ClrDraw', 'While', 'Line', 'If', 'Then', 'Else', and 'End' mustbe entered from the 'PGRM' menus; 'Y_{1}' must be enteredfrom the '2^{nd} Y-vars' menu; '' is entered by pressing the 'STO>' key; and all text, label andvariable names are typed in from 'ALPHA' mode. Everything else is entered as a singlekeystroke on the calculator (for example, '+' is entered by pressing the '+' key).

## Program:

SLOPEFIE uses the plot parameters set in the WINDOW function (Xscl and Yscl are used asthe sample grid size).' The value of mustbe typed (in the equation mode ), as . Forexample, in the given program, , so .

NOTICE: In writing this equation, you CANNOT use 'Y' as the second variable; instead,you must use the ALPHA key to type 'V' (remember: 'V' for 'vertical coordinate'). The TI82 will not accept a variable named 'Y' in this context.

Check: The slope field for , for

xmin = -3, xmax =3, xscl = 0.3, ymin = -2, ymax =2, yscl = 0.3

is sketched on the right.

(jac) Lastrevised: December 03, 1998