# Question:Animated phase portrait with only the point moving

## Question:Animated phase portrait with only the point moving

Maple

Hi everyone,

I want to draw a phase portrait of a particle to see it moving but I don't want to see its trajectory. I don't know how to explain, here is what I did:

restart;with(DEtools), with(plots), with(linalg):

g11:=1;g21:=g11;

z:=exp(I*((t/(2*Pi))+(Pi*j)));

f1:=evalc(Re((I/(2*Pi))*((g11/(subs(j=1,z)-(x(t)+I*y(t))))+(g21/(subs(j=2,z)-(x(t)+I*y(t)))))));

q1:=evalc(-1*Im((I/(2*Pi))*((g11/(subs(j=1,z)-(x(t)+I*y(t))))+(g21/(subs(j=2,z)-(x(t)+I*y(t)))))));

sys1:=[diff(x(t),t)=f1,diff(y(t),t)=q1]:

DEplot(sys1, [x(t), y(t)], t = 0 .. 500, [[x(0) =0, y(0) = 1]],linecolor = blue, thickness = 1, stepsize = 0.5, arrows = medium, color = red,animatecurves=true);

If you plot the last command, you will see the point moving but also its trajectory since t=0. I don't want to keep the histoiry of the movement but only where is the point at the instant t.

If it is not clear, please ask me I will try to be more explicit.

Thank you.

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