3 bodies problem-programming in C

[d_m]

Hello.

I have been folowing this forum for a while, but this is the 1st time I post. If I make any spelling mistakes, forgive me because I'm not an english born speaker.

My problem is the following, I have to write this program in C, and the graphical part is to be made in allegro or GTK+.

The program has 2 fixes masses, m1 and m2, over a rect horizontal line in the middle of the window, in which both the value of the masses as well as their distances are given by the user, and a 3rd mass, m3. The program will have to trace the movement of m3 in the gravitical field created by m1 and m2, oce the user gives the initial speed and position of m3 in the xy field.

I already know that i must 1st calculate the resultant force in m3, using F = G (m1.m2)/r². Then I think I will have to use the equation F = m (d² x(t))/(dt²) to get the position and speed of m3, but I'm not sure about how this is done.

My biggest problem is not about the mathematical/physical part of the problem, is about the programming part, because I'm not very good in programming in C.

Can anyone help me with this?

Thank you

 

[d_m]

So far I have only done this:

#include <stdlib.h>
#include <stdio.h>
#include <math.h>

main(int argc, char* argv[])
{
double x[101];
double y[101];
double m1;
double m2;
double ax[101];
double ay[101];
double x0;
double y0;
double vx0;
double vy0;
double dt;
int n;
FILE *output;

output = fopen("data.dat", "w");

sscanf(argv[1], "%f", &m1);
sscanf(argv[2], "%f", &m2);
sscanf(argv[3], "%f", &x0);
sscanf(argv[4], "%f", &y0);
sscanf(argv[5], "%f", &vx0);
sscanf(argv[6], "%f", &vy0);

dt=0.005;

x[0]=x0;
y[0]=y0;
x[1]=x0 + vx0*dt;
y[1]=y0 + vy0*dt;

printf("%lf %lf\n", x[1], y[1]);

for(n=1; n < 100; ++n)
{
ax[n]= ?
ay[n]= ?

x[n+1]= ?
y[n+1]= ?

fprintf(output, "%f %f\n", x[n+1],y[n+1]);

}
printf("%f %f", ax[1], ay[1]);

fclose(output);

return 0;
}



I'm not sure what i have tu put in ax[n], ay[n], x[n+1] and y[n+1], and I'm also sure about where I will use the gravitational field formula.

 

[Mene]

for sharing your problem with us. I would approach this problem by first breaking it down into smaller, more manageable parts. The first step would be to familiarize myself with the programming language C and the libraries I will be using (Allegro or GTK+). This could involve researching online, reading tutorials, or seeking guidance from more experienced programmers.

Next, I would focus on the mathematical/physical aspect of the problem. As you mentioned, the first step would be to calculate the resultant force on m3 using the formula F = G (m1.m2)/r2. Then, I would use the equation F = m (d2 x(t))/(dt2) to calculate the position and speed of m3 at different time intervals. This could involve using loops and arrays in the programming language to keep track of the changing values.

I would also recommend breaking down the problem into smaller steps and testing each step as you go along. This will help you identify any errors or bugs in your code and make it easier to troubleshoot.

Additionally, I would suggest seeking help from other programmers or joining online forums or communities where you can ask for advice or guidance. Collaboration and learning from others is a valuable tool in problem-solving.

In conclusion, tackling a complex problem like the 3 bodies problem in programming can be challenging, but by breaking it down into smaller steps and seeking help when needed, you can successfully complete the task. Good luck with your project!