Texas Instruments TI-86 - Manual (Page 149)

Chapter 10: Differential Equation Graphing
137
10DIFFEQ.DOC TI-86, Chap 10, US English Bob Fedorisko Revised: 02/13/01 2:28 PM Printed: 02/13/01 3:02 PM Page 137 of 20 10DIFFEQ.DOC TI-86, Chap 10, US English Bob Fedorisko Revised: 02/13/01 2:28 PM Printed: 02/13/01 3:02 PM Page 137 of 20 10DIFFEQ.DOC TI-86, Chap 10, US English Bob Fedorisko Revised: 02/13/01 2:28 PM Printed: 02/13/01 3:02 PM Page 137 of 20
Setting the Axes
To display the axes editor, select AXES from the GRAPH menu in DifEq mode (6 )).
x= assigns a variable to the x-axis
y= assigns a variable to the y-axis
dTime= specifies a point in time (real number)
fldRes= (resolution) sets number of rows (1 through 25)
At the x= and y= prompts, you can enter the independent variable t , as well as Q , Q' , Q n , or
Q' n , where n is an integer ‚ 1 and  9. If you assign t to one axis and Q n or Q' n to the other
axis, only the equation stored to Q n or Q' n is plotted; other differential equations in the
equation editor are not plotted; their selection status is ignored. dTime is only valid for
second-order equations with t in either equation.
The axes editor and defaults for each field format are shown below. When SlpFld field
format is set, the x-axis is always t , so the AXES: SlpFld editor does not display x=t .
When SlpFld format is set: When DirFld format is set: When FldOff format is set:
Differential Equation Graphing Tips
♦
Since the TI -86 plots slope fields and direction fields before it plots equations, you can
press b to pause the graph and view the fields with no solutions plotted.
♦
If you do not specify initial conditions for the equations assigned to the axes, the TI -86
simply draws the field and stops. This gives you access to both the field format options
and the interactive initial conditions simultaneously.
Axes information is stored to
GDB
and PIC variables.