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RE: Help-directional fields

  • To: mathgroup at smc.vnet.net
  • Subject: [mg40325] RE: [mg40312] Help-directional fields
  • From: "David Park" <djmp at earthlink.net>
  • Date: Tue, 1 Apr 2003 04:52:17 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Freddy,

We have dy/dx == Sin[x-y] or dy == Sin[x-y]dx. So our slope field is {dx,dy}
== {dx,Sin[x-y]dx} == dx{1,Sin[x-y]}. Take dx == 1 and the vector field
is...

field[x_, y_] := {1, Sin[x - y]}

We can then plot with...

Needs["Graphics`PlotField`"]
Needs["Graphics`Colors`"]

PlotVectorField[field[x, y], {x, -Pi, Pi}, {y, -Pi, Pi},
    Frame -> True,
    FrameLabel -> {x, y},
    PlotLabel -> y'[x] == Sin[x - y],
    Axes -> True,
    AxesStyle -> LightBlue,
    Background -> Linen,
    ImageSize -> 500];

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/




From: Freddy [mailto:alligatoralligator at hotmail.com]
To: mathgroup at smc.vnet.net

Hi, I am trying to plot a directional field plot for the DE
y'=sin(x-y). The question suggests using a viewing window such as
-10=x=10, -10=y=10  I have spent hours and hours trying to get this to
work, but I must be doing something wrong.  Can anyone please, please
help me with typing the right commands?



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