Solving 2nd degree differntial equatation

[Maverick]

Hi i have a problem with following task. I need to implement Verlet method
and RungeKutta and use it to calculate : x(t)''+k*sin(x(t))=0 with fixed k. 
And Verlet method is:
v_{n+1/2}=v_{n}-h/2*k*sin(x(t))
x_{n+1}=x_{n}+h*v_{n+1/2}
v_{n+1}=v_{n+1/2}-h/2*k*sin(x(t))
and v is x'

The problem is that my Verlet gives different numbers than RungeKutta
method(I think this one is correct as lsode() gives same answer). 


I post my implementation here: 
http://pastebin.com/iZ50BGMW <http://pastebin.com/iZ50BGMW>  
http://pastebin.com/EfPRmG3u <http://pastebin.com/EfPRmG3u>  
http://pastebin.com/gEHxKm2V <http://pastebin.com/gEHxKm2V>  

and in attchments:
Verlet.m <http://octave.1599824.n4.nabble.com/file/n4677408/Verlet.m>  
RK4.m <http://octave.1599824.n4.nabble.com/file/n4677408/RK4.m>  
Project.m <http://octave.1599824.n4.nabble.com/file/n4677408/Project.m>  



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