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Re: Question about how to graph the vector field for the differential

  • To: mathgroup at smc.vnet.net
  • Subject: [mg97960] Re: Question about how to graph the vector field for the differential
  • From: dh <dh at metrohm.com>
  • Date: Thu, 26 Mar 2009 05:25:02 -0500 (EST)
  • References: <gq7j9f$qeo$1@smc.vnet.net>


Hi,

the direction field is plotted by:

dir[x_, y_] := Normalize[{1, 2 x - y}]

VectorPlot[dir[x, y], {x, -3, 3}, {y, -3, 3}]

The velocity field:

vel[x_, y_] := {1, 2 x - y}

VectorPlot[vel[x, y], {x, -3, 3}, {y, -3, 3}]

The stream field:

vel[x_, y_] := {1, 2 x - y}

StreamPlot[vel[x, y], {x, -3, 3}, {y, -3, 3}]

hope this helps, Daniel



jo1e984 at gmail.com wrote:

> i need to graph the vector field and the family of solutions for the

> DE: dy/dx=2x-y

> and i tried the graph the vector field, but while i tried to use the

> VectorFieldPlot it show up some kind of wierd graph...

> and i cannot even get start on the "family of Solutions"

> graph...searched online but still cannot figure out.

> hope some pros can help me out on this...thx alot~!!

> Bluefly

> 




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