Texas Instruments TI-89 사용자 설명서

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Differential Equation Graphing
 451
Fields=FLDOFF
Fields=FLDOFF
Fields=FLDOFF
Fields=FLDOFF
In the Graph 
screen
If the direction field is drawn but no curve is plotted, enter 
initial conditions in the Y= Editor or select one interactively 
from the Graph screen.  If you did enter initial conditions, 
select ZoomFit:
@
„ j
A 
The ncurves Window variable is ignored with DIRFLD. 
Default curves are not drawn automatically.
Notes
With DIRFLD, the equations referenced by the custom axes 
determine which equations are graphed, regardless of which 
equations are selected in the Y= Editor.
If your system of equations refers to t, the direction field (not 
the plotted curves) is drawn with respect to one particular 
time, which is set by the dtime Window variable.
In the 
Y= Editor
If you enter a 2nd- or higher-order equation, enter it as a valid 
system of equations.  
All equations (selected or not) must have the same number of 
initial conditions. Otherwise, a Dimension error occurs when 
you graph.
To set Axes = TIME or CUSTOM, press:
@
2