TI-82 Program:  DIRFIELD

This program will allow plot a direction field or slope
field for a given first order linear differential
equation. You can display a slope field, display the
slope field and the plot of the solution by Euler's
method, approximate a value using Euler's method.

1. Before you run the program, store f(x) in y1 and set
   the desired graph window.
2. Run the program, respond yes to the questions if you 
   did step 1, otherwise no and do step 1.  When entering
   the equation, be sure use X and/or Y.
3. Select SLOPE FIELD to plot a slope field.
4. Select DRAW SOLUTION to draw an approximate solution.  Work
   your way down the menu, (X0,Y0)-enter the initial value,
   INCREMENT-enter the step (delta x), and DRAW CURVE.
5. Select APPROX. Y to approximate a solution using Euler's
   method.  (X0,Y0)-enter the initial condition, INCREMENT-
   enter the step (delta x), X1-enter the x-coordinate, and\
   APPROX. Y(X1)-to approximate y at X1.


Last updated: 3/31/98