GNU Octave, version 2.1.40 (i386-redhat-linux-gnu).
Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002 John W. Eaton.
This is free software; see the source code for copying conditions.
There is ABSOLUTELY NO WARRANTY; not even for MERCHANTIBILITY or
FITNESS FOR A PARTICULAR PURPOSE.  For details, type `warranty'.

Please contribute if you find this software useful.
For more information, visit http://www.octave.org/help-wanted.html

Report bugs to <bug-octave@bevo.che.wisc.edu>.

octave> twobody([1;2;3;4], 1)
xdot = 3
xdot =

  3
  4

rv =

  1
  2

d = 125
xdot =

   3.0000000
   4.0000000
  -0.0080000

xdot =

   3.0000000
   4.0000000
  -0.0080000
  -0.0160000

ans =

   3.0000000
   4.0000000
  -0.0080000
  -0.0160000

octave> twobody([1;2;3;4], 1)
ans =

   3.0000000
   4.0000000
  -0.0080000
  -0.0160000

octave> twobody([1;0;1;0], 1)
ans =

   1
   0
  -1
  -0

octave> twobody([2;0;1;0], 1)
ans =

   2
   0
  -1
  -0

octave> twobody([2;0;1;0], 1)
ans =

   1.00000
   0.00000
  -0.03125
  -0.00000

octave> norm([1,2])
ans = 2.2361
octave> y = lsode("twobody", [1;0;1;0], linspace(0, 5, 100));
ans =

   1.00000   0.00000   1.00000   0.00000
   1.04927   0.00000   0.95189   0.00000
   1.09622   0.00000   0.90799   0.00000
   1.14105   0.00000   0.86763   0.00000
   1.18391   0.00000   0.83025   0.00000
   1.22495   0.00000   0.79543   0.00000
   1.26429   0.00000   0.76283   0.00000
   1.30204   0.00000   0.73216   0.00000
   1.33828   0.00000   0.70318   0.00000
   1.37309   0.00000   0.67570   0.00000
   1.40655   0.00000   0.64955   0.00000
   1.43872   0.00000   0.62460   0.00000
   1.46966   0.00000   0.60071   0.00000
   1.49942   0.00000   0.57780   0.00000
   1.52804   0.00000   0.55576   0.00000
   1.55557   0.00000   0.53451   0.00000
   1.58204   0.00000   0.51399   0.00000
   1.60750   0.00000   0.49414   0.00000
   1.63197   0.00000   0.47489   0.00000
   1.65548   0.00000   0.45619   0.00000
   1.67805   0.00000   0.43801   0.00000
   1.69973   0.00000   0.42031   0.00000
   1.72052   0.00000   0.40304   0.00000
   1.74045   0.00000   0.38618   0.00000
   1.75953   0.00000   0.36968   0.00000
   1.77779   0.00000   0.35354   0.00000
   1.79525   0.00000   0.33772   0.00000
   1.81191   0.00000   0.32219   0.00000
   1.82780   0.00000   0.30694   0.00000
   1.84292   0.00000   0.29195   0.00000
   1.85729   0.00000   0.27720   0.00000
   1.87092   0.00000   0.26266   0.00000
   1.88383   0.00000   0.24833   0.00000
   1.89601   0.00000   0.23419   0.00000
   1.90748   0.00000   0.22023   0.00000
   1.91826   0.00000   0.20643   0.00000
   1.92834   0.00000   0.19278   0.00000
   1.93773   0.00000   0.17926   0.00000
   1.94645   0.00000   0.16587   0.00000
   1.95449   0.00000   0.15260   0.00000
   1.96186   0.00000   0.13942   0.00000
   1.96857   0.00000   0.12635   0.00000
   1.97463   0.00000   0.11336   0.00000
   1.98003   0.00000   0.10044   0.00000
   1.98477   0.00000   0.08759   0.00000
   1.98887   0.00000   0.07480   0.00000
   1.99233   0.00000   0.06205   0.00000
   1.99514   0.00000   0.04934   0.00000
   1.99731   0.00000   0.03667   0.00000
   1.99885   0.00000   0.02402   0.00000
   1.99974   0.00000   0.01139   0.00000
   2.00000   0.00000  -0.00124   0.00000
   1.99962   0.00000  -0.01387   0.00000
   1.99860   0.00000  -0.02650   0.00000
   1.99694   0.00000  -0.03916   0.00000
   1.99464   0.00000  -0.05184   0.00000
   1.99170   0.00000  -0.06455   0.00000
   1.98812   0.00000  -0.07730   0.00000
   1.98389   0.00000  -0.09011   0.00000
   1.97902   0.00000  -0.10297   0.00000
   1.97349   0.00000  -0.11590   0.00000
   1.96731   0.00000  -0.12891   0.00000
   1.96047   0.00000  -0.14200   0.00000
   1.95296   0.00000  -0.15519   0.00000
   1.94479   0.00000  -0.16849   0.00000
   1.93594   0.00000  -0.18190   0.00000
   1.92641   0.00000  -0.19545   0.00000
   1.91620   0.00000  -0.20913   0.00000
   1.90529   0.00000  -0.22296   0.00000
   1.89367   0.00000  -0.23696   0.00000
   1.88135   0.00000  -0.25113   0.00000
   1.86830   0.00000  -0.26550   0.00000
   1.85453   0.00000  -0.28008   0.00000
   1.84001   0.00000  -0.29488   0.00000
   1.82474   0.00000  -0.30992   0.00000
   1.80870   0.00000  -0.32522   0.00000
   1.79188   0.00000  -0.34080   0.00000
   1.77427   0.00000  -0.35669   0.00000
   1.75585   0.00000  -0.37290   0.00000
   1.73660   0.00000  -0.38946   0.00000
   1.71650   0.00000  -0.40640   0.00000
   1.69554   0.00000  -0.42375   0.00000
   1.67369   0.00000  -0.44155   0.00000
   1.65093   0.00000  -0.45982   0.00000
   1.62724   0.00000  -0.47862   0.00000
   1.60258   0.00000  -0.49799   0.00000
   1.57692   0.00000  -0.51797   0.00000
   1.55024   0.00000  -0.53863   0.00000
   1.52250   0.00000  -0.56002   0.00000
   1.49366   0.00000  -0.58223   0.00000
   1.46368   0.00000  -0.60533   0.00000
   1.43250   0.00000  -0.62941   0.00000
   1.40008   0.00000  -0.65459   0.00000
   1.36636   0.00000  -0.68099   0.00000
   1.33127   0.00000  -0.70875   0.00000
   1.29475   0.00000  -0.73804   0.00000
   1.25669   0.00000  -0.76908   0.00000
   1.21703   0.00000  -0.80209   0.00000
   1.17564   0.00000  -0.83738   0.00000
   1.13240   0.00000  -0.87531   0.00000

octave> y = lsode("twobody", [1;0;1;0], linspace(0, 50, 1000));
octave> plot(y(:,1:2))
octave> y = lsode("twobody", [1;0;1;0], linspace(0, 50, 1000));
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1841431856185E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1841431856185E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1841431856185E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1841431856185E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1841431856185E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1528653201831E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1528653201831E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1528653201831E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1528653201831E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1528653201831E-18
 LSODE--  ABOVE WARNING HAS BEEN ISSUED I1 TIMES.  
       IT WILL NOT BE ISSUED AGAIN FOR THIS PROBLEM
      In above message,  I1 =        10
plot(y(:,1:2))


octave> octave> octave> plot(y(:,1), y(:,2))
octave> Warning: empty y range [0:0], adjusting to [-1:1]

octave> 
octave> y(1:10, :)
ans =

  1.00000  0.00000  1.00000  0.00000
  1.04927  0.00000  0.95189  0.00000
  1.09622  0.00000  0.90799  0.00000
  1.14105  0.00000  0.86763  0.00000
  1.18391  0.00000  0.83025  0.00000
  1.22495  0.00000  0.79543  0.00000
  1.26429  0.00000  0.76283  0.00000
  1.30204  0.00000  0.73216  0.00000
  1.33828  0.00000  0.70318  0.00000
  1.37309  0.00000  0.67570  0.00000

octave> y(1:100, :)
ans =

   1.00000   0.00000   1.00000   0.00000
   1.04927   0.00000   0.95189   0.00000
   1.09622   0.00000   0.90799   0.00000
   1.14105   0.00000   0.86763   0.00000
   1.18391   0.00000   0.83025   0.00000
   1.22495   0.00000   0.79543   0.00000
   1.26429   0.00000   0.76283   0.00000
   1.30204   0.00000   0.73216   0.00000
   1.33828   0.00000   0.70318   0.00000
   1.37309   0.00000   0.67570   0.00000
   1.40655   0.00000   0.64955   0.00000
   1.43872   0.00000   0.62460   0.00000
   1.46966   0.00000   0.60071   0.00000
   1.49942   0.00000   0.57780   0.00000
   1.52804   0.00000   0.55576   0.00000
   1.55557   0.00000   0.53451   0.00000
   1.58204   0.00000   0.51399   0.00000
   1.60750   0.00000   0.49414   0.00000
   1.63197   0.00000   0.47489   0.00000
   1.65548   0.00000   0.45619   0.00000
   1.67805   0.00000   0.43801   0.00000
   1.69973   0.00000   0.42031   0.00000
   1.72052   0.00000   0.40304   0.00000
   1.74045   0.00000   0.38618   0.00000
   1.75953   0.00000   0.36968   0.00000
   1.77779   0.00000   0.35354   0.00000
   1.79525   0.00000   0.33772   0.00000
   1.81191   0.00000   0.32219   0.00000
   1.82780   0.00000   0.30694   0.00000
   1.84292   0.00000   0.29195   0.00000
   1.85729   0.00000   0.27720   0.00000
   1.87092   0.00000   0.26266   0.00000
   1.88383   0.00000   0.24833   0.00000
   1.89601   0.00000   0.23419   0.00000
   1.90748   0.00000   0.22023   0.00000
   1.91826   0.00000   0.20643   0.00000
   1.92834   0.00000   0.19278   0.00000
   1.93773   0.00000   0.17926   0.00000
   1.94645   0.00000   0.16587   0.00000
   1.95449   0.00000   0.15260   0.00000
   1.96186   0.00000   0.13942   0.00000
   1.96857   0.00000   0.12635   0.00000
   1.97463   0.00000   0.11336   0.00000
   1.98003   0.00000   0.10044   0.00000
   1.98477   0.00000   0.08759   0.00000
   1.98887   0.00000   0.07480   0.00000
   1.99233   0.00000   0.06205   0.00000
   1.99514   0.00000   0.04934   0.00000
   1.99731   0.00000   0.03667   0.00000
   1.99885   0.00000   0.02402   0.00000
   1.99974   0.00000   0.01139   0.00000
   2.00000   0.00000  -0.00124   0.00000
   1.99962   0.00000  -0.01387   0.00000
   1.99860   0.00000  -0.02650   0.00000
   1.99694   0.00000  -0.03916   0.00000
   1.99464   0.00000  -0.05184   0.00000
   1.99170   0.00000  -0.06455   0.00000
   1.98812   0.00000  -0.07730   0.00000
   1.98389   0.00000  -0.09011   0.00000
   1.97902   0.00000  -0.10297   0.00000
   1.97349   0.00000  -0.11590   0.00000
   1.96731   0.00000  -0.12891   0.00000
   1.96047   0.00000  -0.14200   0.00000
   1.95296   0.00000  -0.15519   0.00000
   1.94479   0.00000  -0.16849   0.00000
   1.93594   0.00000  -0.18190   0.00000
   1.92641   0.00000  -0.19545   0.00000
   1.91620   0.00000  -0.20913   0.00000
   1.90529   0.00000  -0.22296   0.00000
   1.89367   0.00000  -0.23696   0.00000
   1.88135   0.00000  -0.25113   0.00000
   1.86830   0.00000  -0.26550   0.00000
   1.85453   0.00000  -0.28008   0.00000
   1.84001   0.00000  -0.29488   0.00000
   1.82474   0.00000  -0.30992   0.00000
   1.80870   0.00000  -0.32522   0.00000
   1.79188   0.00000  -0.34080   0.00000
   1.77427   0.00000  -0.35669   0.00000
   1.75585   0.00000  -0.37290   0.00000
   1.73660   0.00000  -0.38946   0.00000
   1.71650   0.00000  -0.40640   0.00000
   1.69554   0.00000  -0.42375   0.00000
   1.67369   0.00000  -0.44155   0.00000
   1.65093   0.00000  -0.45982   0.00000
   1.62724   0.00000  -0.47862   0.00000
   1.60258   0.00000  -0.49799   0.00000
   1.57692   0.00000  -0.51797   0.00000
   1.55024   0.00000  -0.53863   0.00000
   1.52250   0.00000  -0.56002   0.00000
   1.49366   0.00000  -0.58223   0.00000
   1.46368   0.00000  -0.60533   0.00000
   1.43250   0.00000  -0.62941   0.00000
   1.40008   0.00000  -0.65459   0.00000
   1.36636   0.00000  -0.68099   0.00000
   1.33127   0.00000  -0.70875   0.00000
   1.29475   0.00000  -0.73804   0.00000
   1.25669   0.00000  -0.76908   0.00000
   1.21703   0.00000  -0.80209   0.00000
   1.17564   0.00000  -0.83738   0.00000
   1.13240   0.00000  -0.87531   0.00000

octave> plot(y(1:500, :))
error: invalid row index = 1000
error: evaluating argument list element number 1
octave> y(1:500,:)
error: invalid row index = 500
error: evaluating argument list element number 1
octave> y(1:500,:)
error: invalid row index = 500
octave> y
y =

   1.00000   0.00000   1.00000   0.00000
   1.04927   0.00000   0.95189   0.00000
   1.09622   0.00000   0.90799   0.00000
   1.14105   0.00000   0.86763   0.00000
   1.18391   0.00000   0.83025   0.00000
   1.22495   0.00000   0.79543   0.00000
   1.26429   0.00000   0.76283   0.00000
   1.30204   0.00000   0.73216   0.00000
   1.33828   0.00000   0.70318   0.00000
   1.37309   0.00000   0.67570   0.00000
   1.40655   0.00000   0.64955   0.00000
   1.43872   0.00000   0.62460   0.00000
   1.46966   0.00000   0.60071   0.00000
   1.49942   0.00000   0.57780   0.00000
   1.52804   0.00000   0.55576   0.00000
   1.55557   0.00000   0.53451   0.00000
   1.58204   0.00000   0.51399   0.00000
   1.60750   0.00000   0.49414   0.00000
   1.63197   0.00000   0.47489   0.00000
   1.65548   0.00000   0.45619   0.00000
   1.67805   0.00000   0.43801   0.00000
   1.69973   0.00000   0.42031   0.00000
   1.72052   0.00000   0.40304   0.00000
   1.74045   0.00000   0.38618   0.00000
   1.75953   0.00000   0.36968   0.00000
   1.77779   0.00000   0.35354   0.00000
   1.79525   0.00000   0.33772   0.00000
   1.81191   0.00000   0.32219   0.00000
   1.82780   0.00000   0.30694   0.00000
   1.84292   0.00000   0.29195   0.00000
   1.85729   0.00000   0.27720   0.00000
   1.87092   0.00000   0.26266   0.00000
   1.88383   0.00000   0.24833   0.00000
   1.89601   0.00000   0.23419   0.00000
   1.90748   0.00000   0.22023   0.00000
   1.91826   0.00000   0.20643   0.00000
   1.92834   0.00000   0.19278   0.00000
   1.93773   0.00000   0.17926   0.00000
   1.94645   0.00000   0.16587   0.00000
   1.95449   0.00000   0.15260   0.00000
   1.96186   0.00000   0.13942   0.00000
   1.96857   0.00000   0.12635   0.00000
   1.97463   0.00000   0.11336   0.00000
   1.98003   0.00000   0.10044   0.00000
   1.98477   0.00000   0.08759   0.00000
   1.98887   0.00000   0.07480   0.00000
   1.99233   0.00000   0.06205   0.00000
   1.99514   0.00000   0.04934   0.00000
   1.99731   0.00000   0.03667   0.00000
   1.99885   0.00000   0.02402   0.00000
   1.99974   0.00000   0.01139   0.00000
   2.00000   0.00000  -0.00124   0.00000
   1.99962   0.00000  -0.01387   0.00000
   1.99860   0.00000  -0.02650   0.00000
   1.99694   0.00000  -0.03916   0.00000
   1.99464   0.00000  -0.05184   0.00000
   1.99170   0.00000  -0.06455   0.00000
   1.98812   0.00000  -0.07730   0.00000
   1.98389   0.00000  -0.09011   0.00000
   1.97902   0.00000  -0.10297   0.00000
   1.97349   0.00000  -0.11590   0.00000
   1.96731   0.00000  -0.12891   0.00000
   1.96047   0.00000  -0.14200   0.00000
   1.95296   0.00000  -0.15519   0.00000
   1.94479   0.00000  -0.16849   0.00000
   1.93594   0.00000  -0.18190   0.00000
   1.92641   0.00000  -0.19545   0.00000
   1.91620   0.00000  -0.20913   0.00000
   1.90529   0.00000  -0.22296   0.00000
   1.89367   0.00000  -0.23696   0.00000
   1.88135   0.00000  -0.25113   0.00000
   1.86830   0.00000  -0.26550   0.00000
   1.85453   0.00000  -0.28008   0.00000
   1.84001   0.00000  -0.29488   0.00000
   1.82474   0.00000  -0.30992   0.00000
   1.80870   0.00000  -0.32522   0.00000
   1.79188   0.00000  -0.34080   0.00000
   1.77427   0.00000  -0.35669   0.00000
   1.75585   0.00000  -0.37290   0.00000
   1.73660   0.00000  -0.38946   0.00000
   1.71650   0.00000  -0.40640   0.00000
   1.69554   0.00000  -0.42375   0.00000
   1.67369   0.00000  -0.44155   0.00000
   1.65093   0.00000  -0.45982   0.00000
   1.62724   0.00000  -0.47862   0.00000
   1.60258   0.00000  -0.49799   0.00000
   1.57692   0.00000  -0.51797   0.00000
   1.55024   0.00000  -0.53863   0.00000
   1.52250   0.00000  -0.56002   0.00000
   1.49366   0.00000  -0.58223   0.00000
   1.46368   0.00000  -0.60533   0.00000
   1.43250   0.00000  -0.62941   0.00000
   1.40008   0.00000  -0.65459   0.00000
   1.36636   0.00000  -0.68099   0.00000
   1.33127   0.00000  -0.70875   0.00000
   1.29475   0.00000  -0.73804   0.00000
   1.25669   0.00000  -0.76908   0.00000
   1.21703   0.00000  -0.80209   0.00000
   1.17564   0.00000  -0.83738   0.00000
   1.13240   0.00000  -0.87531   0.00000

octave> y = lsode("twobody", [1;0;1;0], linspace(0, 50, 1000));
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1841431856185E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1841431856185E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1841431856185E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1841431856185E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1841431856185E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1528653201831E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1528653201831E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1528653201831E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1528653201831E-18
 LSODE--  WARNING..INTERNAL T (=R1) AND H (=R2) ARE
       SUCH THAT IN THE MACHINE, T + H = T ON THE NEXT STEP  
       (H = STEP SIZE). SOLVER WILL CONTINUE ANYWAY
      In above,  R1 =  0.5712388512224E+01   R2 =  0.1528653201831E-18
 LSODE--  ABOVE WARNING HAS BEEN ISSUED I1 TIMES.  
       IT WILL NOT BE ISSUED AGAIN FOR THIS PROBLEM
      In above message,  I1 =        10
octave> y = lsode("twobody", [1;1;1;0], linspace(0, 50, 1000));
octave> plot(y(:,1), y(:,2))
octave> y = lsode("twobody", [1;1;1;0], linspace(0, 50, 1000));
error: `fric' undefined near line 6 column 26
error: evaluating binary operator `*' near line 6, column 31
error: evaluating binary operator `-' near line 6, column 24
error: evaluating assignment expression near line 6, column 11
error: called from `twobody' in file `/home/marek/CourseDir/481/Octave/twobody.m'
error: lsode: evaluation of user-supplied function failed
error: lsode: inconsistent sizes for state and derivative vectors
error: evaluating assignment expression near line 21, column 3
octave> y = lsode("twobody", [1;1;1;0], linspace(0, 50, 1000));
octave> plot(y(:,1), y(:,2))
octave> y = lsode("twobody", [1;1;1;0], linspace(0, 250, 2000));
octave> plot(y(:,1), y(:,2))
octave> y = lsode("twobody", [1;1;1;0], linspace(0, 250, 2000));
octave> plot(y(:,1:2))
octave> plot(y(:,1), y(:,2))
octave> plot(y(:,1:2))
octave> plot(y(:,1), y(:,2))
octave>