SLOPE FIELD - TI 85

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
:ClDrw  {ClDrw is in GRAPH under Draw}
:FnOff  {FnOff is in GRAPH under Vars}
:7*(xMax-xMin)/83$\to$H        {xMax, xMin are in GRAPH under Range} {The arrow is STO}
:7*(yMax-yMin)/55$\to$K  {yMax, yMin are in GRAPH under Range}
:1/(0.4*H)^2$\to$A 
:1/(0.4*K)^2$\to$B 
:xMin+0.5*H$\to$x  {x is x-VAR}
:yMin+0.5*K$\to$Z 
:1$\to$L  {The 1 is a one}
:Lbl P  {Lbl is in PRGM under CTL}
:1$\to$J 
:Z$\to$y  {y is in GRAPH under Vars}
:Lbl Q 
:y1$\to$T  {y1 is in VARS under EQU}
: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 GRAPH under Draw}
:Z+J*K$\to$y 
:IS>(J,8)  {IS> if in PRGM under CTL}
:Goto Q  {Goto is in PRGM under CTL}
:x+H$\to$x 
:IS>(L,12) 
:Goto P 

Running the Program
 
You will need to enter a function  f(x,y) into y1 and adjust the RANGE accordingly before running the program. You can use the x and y shown in the GRAPH menu.