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MathGroup Archive 2007

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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[0] == poc0[[1]],

>         y[0] == poc0[[2]]

>         },

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

> 

> but this wont work, any suggestions?

> 



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