Question: Newmark Method

Hi everybody,

I'm an mechanical enginer and I have to solve numerically this kind of differential equation : m(d2z/dt2)+c(dz/dt) + k*z = F where z is the displacement.
The best resolution for this problem is to use a Newmark method (which is available here at page 10 http://www.google.fr/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&ved=0CEEQFjAE&url=http%3A%2F%2Fpole-modelisation.univ-bpclermont.fr%2Fcisssi%2Findex.php%3Foption%3Dcom_docman%26task%3Ddoc_download%26gid%3D110%26Itemid%3D51&ei=8seqU5-wEaS00wXm14G4CA&usg=AFQjCNFerFoQ4O-nrIdOoUiX7SIkLMb6sA&sig2=MZ6BxmUPm7Gg3CGcH4nknQ&bvm=bv.69620078,d.d2k)

So I have written this method in Maple but nothing happen and I don't where the mistakes are. So if somebody could help me, that will be great.

My code is :