SLOPE FIELD - TI 81

Introduction
This program plots the slope field for the differential equation in the form ${\hbox{dy}\over \hbox{dx}}=\hbox{f(x,y)}$.
 
If you have not used one of the programs posted on this website before, you should read through the information in the Intro to Programming section first.

The Program
:ClrDraw  {ClrDraw is in DRAW under Draw}
:All-Off  {All-Off is in Y-VARS under OFF}
:7*(XMax-XMin)/83$\to$H        {XMax, XMin are in VARS under RNG} {The arrow is STO}
:7*(YMax-YMin)/55$\to$K  {YMax, YMin are in VARS under WINDOW}
:1/(0.4*H)^2$\to$A 
:1/(0.4*K)^2$\to$B 
:XMin+0.5*H$\to$X 
:YMin+0.5*K$\to$Z 
:1$\to$L  {The 1 is a one}
:Lbl 1  {Lbl is in PRGM under CTL}
:1$\to$J 
:Z$\to$Y 
:Lbl 2 
:Y1$\to$T  {Y1 is in Y-VARS under FUNCTION}
:1/$\sqrt{}$(A+B*T^2)$\to$C  { is the square root button.} 
:T*C$\to$S 
:Line(X-C,Y-S,X+C,Y+S)  {Line is in DRAW under Draw}
:Z+J*K$\to$Y 
:IS>(J,8)  {IS> if in PRGM under CTL}
:Goto 2  {Goto is in PRGM under CTL}
:X+H$\to$X 
:IS>(L,12) 
:Goto 1 

Running the Program
 
You will need to enter a function  f(x,y) into Y1 and adjust the WINDOW accordingly before running the program. You can use the X,T  button for X and the ALPHA button for Y.