First, I want to thank you.

But, What a pity! Your solve doesn't work

oh, who can help me to solve my problem .... ? Hurry up !!!  T___T

Hello everybody, may you help me, I have one problem ...
I have a function, example y = x^2, and two points and there positions are A(-1,3) and B(2, -2). I want to plot all, I want them have to appear in only a chart, both function and two points. Anyone can help me?

Thanks a lot ...

Oh, Rolf, I can't use any word to my show deep gratitude to you. You're very great !!!

rolffankhauser wrote:

As you can see, you have simulated 1/4 from an ellipse. So you have to simulate 4 times longer or 5 times longer to be sure that you simulate more than 360 degrees.

Thanks Rolf, you can guide me concretely because I'm a beginner, How to simulate, I dont know how to simulate 4 times longer or more.

oh, thanks Rolf once again for guiding me,

You have got a perfect ellipse and that's correct, but, my program can't show a perfect ellipse, only a part of ellipse, I will show you my result:



Once again, may you show to me your "simulate code", how to get a perfect ellipse?

Thanks Rolf

bboymq wrote:

I have a nonlinear Differential Equation for an Orbit of a Satellite
Consider the problem of an orbit of satellite, whose position and velocity are obtained as the solution of the following state equation:

x'₁(t) = x₃(t)
x'₂(t) = x₄(t)
x'₃(t) = -GM_Ex₁(t) / (x²₁(t) + x²₂(t))^3/2
x'₄(t) = -GM_Ex₂(t) / (x²₁(t) + x²₂(t))^3/2

where G = 6.672 x 10^-11 Nm²/kg² is the gravitational constant, and M_E =  6.97 x 10²⁴ kg is the mass of the earth. Note (x₁, x₂) and (x₃, x₄) denote the position and velocity, respectively, of the satellite on the plane having the earth at its origin.

How can I plot them in openModelica? I have tried, but I can't plot them.

Thanks a lot.

Thanks Rolf, can you check my program

(x10,x20) = (4.223 × 107, 0)[m]and (x30,x40) = (v10,v20) =
(0, 3071)[m/s].

Here is the code in modelica

model A
  constant Real G = 6.672e-11;
  constant Real ME = 5.97e24;
  Real x1(start = 4.223e7);
  Real x2(start = 0);
  Real x3(start = 0);
  Real x4(start = 3071);
equation
  der(x1) = x3;
  der(x2) = x4;
  der(x3) = -G * ME * x1 / ((x1^2 + x2^2)^(3/2));
  der(x4) = -G * ME * x2 / ((x1^2 + x2^2)^(3/2));
end A;

Is this program wrong?

Thanks a lot.

I have a nonlinear Differential Equation for an Orbit of a Satellite
Consider the problem of an orbit of satellite, whose position and velocity are obtained as the solution of the following state equation:

x'₁(t) = x₃(t)
x'₂(t) = x₄(t)
x'₃(t) = -GM_Ex₁(t) / (x²₁(t) + x²₂(t))^3/2
x'₄(t) = -GM_Ex₂(t) / (x²₁(t) + x²₂(t))^3/2

where G = 6.672 x 10^-11 Nm²/kg² is the gravitational constant, and M_E =  6.97 x 10²⁴ kg is the mass of the earth. Note (x₁, x₂) and (x₃, x₄) denote the position and velocity, respectively, of the satellite on the plane having the earth at its origin.

How can I plot them in openModelica? I have tried, but I can't plot them.

Thanks a lot.