       Re: directionfields from StreamPlot looks different from solution

• To: mathgroup at smc.vnet.net
• Subject: [mg100624] Re: directionfields from StreamPlot looks different from solution
• From: dh <dh at metrohm.com>
• Date: Tue, 9 Jun 2009 06:37:12 -0400 (EDT)
• References: <h0bteg\$8ge\$1@smc.vnet.net>

```
Hi Sean,

VectorPlot and StreamPlot do not show the same. VectorPlot obviously

plots a vector field, showing vector of different length. StreamPlot on

the other hand does not bother about the size of the vectors (velocity),

it only gives directions. Nevertheless, you must feed StreamPlot with

vectors (velocities).

Daniel

sean_incali at yahoo.com wrote:

> I don't think I'm using StreamPlot properly.

>

> Consider the following non-autonomous ODE

>

> y'[t] == (t^2) - y[t]

>

> Solutions for various ICs can be viewed by the following.

>

> sol= Table[NDSolve[{y'[t] == (t^2) - y[t], y == y0}, y[t], {t, -4,

> 4}], {y0, 0, 6, 0.5}];

>

> Plot[Evaluate[y[t] /. sol], {t, -4, 4}, PlotRange -> {{-4, 4}, {-2,

> 10}}]

>

> Shouldn't Vector fields be similar to the solutions above? If I plot t

> on x-axis vs. t^2-y on y axis...

>

> VectorPlot[{t, (t^2) - y}, {t, -4, 4}, {y, -2, 10}]

>

> StreamPlot[{t, (t^2) - y}, {t, -4, 4}, {y, -2, 10}]

>

> I don't get similar results...

>

> What is the reason for this?

>

>

> Sean

>

>

>

>

```

• Prev by Date: Re: Problem with plotting and simplifying a function
• Next by Date: Re: Dependent dynamic controls
• Previous by thread: Re: directionfields from StreamPlot looks
• Next by thread: creating an array in a loop