       Re: pursuit curve (differential equations)

• To: mathgroup at smc.vnet.net
• Subject: [mg72867] Re: pursuit curve (differential equations)
• From: dh <dh at metrohm.ch>
• Date: Tue, 23 Jan 2007 04:59:16 -0500 (EST)
• References: <ep1sq1\$g13\$1@smc.vnet.net>

```
Hi Trijezni,

you have syntax errors: "." should be "*" and is not necessery.

Functions must be written with arguments. See below.

Daniel

> hi i am doing pursuit curve in mathematica.. for instance, fox is chasing a

> rabbit - rabbit has a certain defined path (for example - a circle

> {cos(t),sin(t)}. fox always heads directly toward the rabbit.

>

> k - relative speed fox/rabbit

> p,q - rabbit's path (for instance a circle {cos(t),sin(t)}

> x,y - fox's path

> t - time :)

>

> soln = NDSolve[

>       {

>         x'[t] == k.Sqrt[p'[t]^2 + q'[t]^2].(p - x[t])

^                         ^

> 		/Sqrt[(p - x[t])^2 + (q - y[t])^2],

^              ^

>         y'[t] == k.Sqrt[p'[t]^2 + q'[t]^2].(y - q[t])

^                         ^

> 		/Sqrt[(p - x[t])^2 + (q - y[t])^2],

^              ^

>         x == poc0[],

>         y == poc0[]

>         },

>       {x[t], y[t]}, {t, t0, t1}];

>

> but this wont work, any suggestions?

>

```

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