SUNY at Stony Brook -- Mathematics Department

Slope fields on the Sharp EL-8300C or EL-8200 Calculator

General: To enter the program into the calculator, press the programming key (middle upper key), then C (which selects the NEW program option), then ENTER, then 1 (to select REAL mode), then the program name. The calculator will be in A-LOCK mode. Hit ALPHA at the end of the name, and then ENTER. After typing each command, press the ENTER key.

Commands:  			Explanation and keying instructions

ClrG				Clears the screen. COMMAND (2ndF MATH),E,1
Goto start			This program begins with a subroutine
				fn which gives the function of x and y
				defining the slope. For Goto and Label 
				press COMMAND, then B for BRNCH menu;
Label fn			then 2 for Goto, 1 for Label.
f=-x/y				ONLY LINE to be changed for a new function
				-x/y is only an example!! Note: f here is a
				function of  both x and y.
Return				For Return, get to BRNCH  mode as above,
				then press 5 key.
Label start			"start" is here.
h=7(-xmin+xmax)/83		Program will prompt for the unspecified
				variables xmin,xmax,ymin,ymax. Remember
				to use the (-) sign next to ENTER.
k=7(-ymin+ymax)/55		For /, press the division key, under the
				the ) key. These instructions calculate the
				x and y increments.		
Range xmin,xmax,1,ymin,ymax,1	For Range, press COMMAND, then D for GRAPH 
				menu, then 4. This instruction will be
				used when drawing the field.
a=1/(0.4h)^2			Instead of ^2 one can press the key
b=1/(0.4k)^2			left of the log key. The numbers a and b are
				used in calculating how long the line segments
				will be.
x=xmin+0.5h			These instructions locate the initial lower
z=ymin+0.5k			left-hand point.
i=1				Initializes the column count.
Label 1
j=1				Initializes the row count for each new column.
y=z		
Label 2
Gosub fn
c=1/sqrt(a+b*f^2)		HERE, DO NOT ENTER THE LETTERS sqrt,
				BUT INSTEAD PRESS THE KEY to the left 
				of the STO key!	Calculator will show a radical.
s=f*c				* is the multiplication key, under the
				( key. The numbers c and s will give the
				horizontal and vertical components of the line.
u=x
v=y
Line u-c,v-s,u+c,v+s		For Line press COMMAND,D,7 key. Note: comma 
				is on the . key, in ALPHA mode. Draws a
				line centered at the current (x.y)
y=v+k				Move up in the column.
j=j+1
If j< =8 Goto 2			For If and Goto go to BRNCH mode as 
				before, then press 3 key for If and 2 key
				for Goto. For < = press COMMAND, then C 
 				for INEQ menu, then 3. Are we still in this 
				column? If so go back to "2".
x=u+h				Otherwise move over to next column.
i=i+1
If i< =12 Goto 1		Check if all columns are done.					
DispG				Display graph: COMMAND (2ndF MATH),E,4

Check: For f = -x/y get circles centered at the origin. The circles will be round if your screen parameters have the correct aspect ratio.
Check: For f = x+y and window [-3,3]x[-2,2], calculator screen should have the image shown on the right.