HP 49g+, Руководство пользователя, Страница: 411 / 862

Page 12-34
•
Press
LL @)PICT
to leave the EDIT environment.
•
Press
@CANCL
to return to the PLOT WINDOW environment. Then, press
$
, or
L @@@OK@@@
, to return to normal calculator display.
Slope fields
Slope fields are used to visualize the solutions to a differential equation of the
form y’ = f(x,y). Basically, what is presented in the plot are segments
tangential to the solution curves, since y’ = dy/dx, evaluated at any point (x,y),
represents the slope of the tangent line at point (x,y).
For example, to visualize the solution to the differential equation y’ = f(x,y) =
x+y, use the following:
•
Press
„ô
, simultaneously if in RPN mode, to access to the PLOT
SETUP window.
•
Change
TYPE
to
Slopefield.
•
Press
˜
and type ‘X+Y’
@@@OK@@@
.
•
Make sure that ‘X’ is selected as the
Indep:
and ‘Y’ as the
Depnd:
variables.
•
Press
L @@@OK@@@
to return to normal calculator display.
•
Press
„ò
, simultaneously if in RPN mode, to access the PLOT
WINDOW screen.
•
Change the plot window ranges to read:
X-Left:-5, X-Right:5, Y-Near:-5, Y-Far:
5
•
Press
@ERASE @DRAW
to draw the slope field plot. Press
@EDIT L
@LABEL @MENU
to see the plot unencumbered by the menu and with
identifying labels.
•
Press
LL @)PICT
to leave the EDIT environment.