MY problom is easy,but i can't get the reasonable answer.problom dipicted:(adsbygoogle = window.adsbygoogle || []).push({});

In the Cartesian coordinates,A satellite'higth is 200KM,and just in two dimensions.the initial position is （-6571KM，0），and initial velocity is （0，-7.8KM/S）.I need the final running solution of program.I want to solve the problom in ode45.The result figure just is a circle

program as following:

============================================

function Yd=orbit(t,y)

global u

rx=y(1);

ry=y(2);

vx=y(3);

vy=y(4);

rr=sqrt(rx^2+ry^2);

vxy=[vx;vy];

xy=[rx;ry];

Yd=[vxy;-u*xy/rr^3];

===================================

function wlow3

global u

u=3.986e14;

t0=0;tf=24*60*60;

tspan=[t0,tf]; %

y0=[-6.571e6;0;0;-7.8e3];%

[t,YY]=ode45('orbit',tspan,y0);

X=YY(:,1);

Y=YY(:,2);

plot(X,Y);

xlabel('x')

ylabel('y')

hold on

axis('image')

==========================================================

I hope anyone who researches orbit or others can communicates with me.

thans a lot.

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# About orbit or ode

Can you offer guidance or do you also need help?

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