HP 49g+ - Manual (Page 411)

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.