Program napisany jest w fortranie. Wykorzystuje on metode Eulera- to rozwiniecie w szereg Taylor'a do wyrazu pierwszego rzedu. Ponizszy kod programu ORBIT prezentuje te metode:
program orbit
implicit none
double precision epsilon,T,X,vx,Y,vy,R,ax,ay,vpolx, vpoly
open(20,file='orbit.dat',status='unknown')
open(21,file='metoda_Eulera.dat',status='unknown')
epsilon = 0.01d0
T = 0.0d0
X = 0.5d0
vx = 0.0d0
Y = 0.0d0
vy = 1.63d0
R = dsqrt(X**2+Y**2)
ax = -X/(R**3)
ay = -Y/(R**3)
vpolx= vx + (epsilon/2)*ax
vpoly = vy + (epsilon/2)*ay
write(20,'(f4.2,5(1x,f6.3))')T,X,ax,Y,ay,R
write(21,'(f4.2,4(1x,a,1x,f6.3))')T,'&',X,'&',ax,'&',Y,'&',ay
10 continue
if(T.lt.2500d0) then
T=T+epsilon
X=X+epsilon*vpolx
Y=Y+epsilon*vpoly
R = dsqrt(X**2+Y**2)
aX = -X/(R**3)
aY = -Y/(R**3)
vpolx = vpolx+epsilon*ax
vpoly = vpoly+epsilon*ay
write(20,'(f4.2,5(1x,f6.3))')T,X,ax,Y,ay,R
write(21,'(f4.2,4(1x,a1,1x,f6.3))')T,'&',X,'&',ax,'&',Y,'&',ay
go to 10
endif
close(20)
close(21)
end