Trouble with newmark method code. its not working and i don't know why. I want to get u,v and a from these equations

Could someone please help. I am trying to write a code for the new mark method but its not working and i can't figure out why.

%Time
ti=0;
dt=0.02;
tf=5.98;
t=ti:dt:tf;
nt=length(t);

%force
for t=0:0.02:6
p0=[0;0;0;132482]*t
p1=p0+[0;0;0;2649.64]
end

%Constants
alpha=0;
beta=0;
a1=alpha+(1/(0.5*dt));
b=beta+(0.5*dt);
c=0.5*dt;
d=(1-0.5)*dt;
e=1/0.5;
f=beta-((1-0.5)*dt);
g=1/(0.5*dt);
h=(1-0.5)/0.5;

%Initial conditions
u(:,1)=zeros;
v(:,1)=zeros;
a(:,1)=zeros;

MM=[1044,0,0,0;0,733.46,0,0;0,0,457.8,0;0,0,0,44.67];
KM=[9900000000,-9893000000,0,0;0,10000000000,-439000000,0;0,0,1370000000,-932200000;0,0,-932200000,932200000];

%time step
for it=1:nt-1
    for t=1:nt-1
p0=[0;0;0;132482]*t;
p1=p0+[0;0;0;2649.64];
    end
    u(:,it+1)=((c*p1)+(d*p0)+(a1*MM*u(:,it))+(e*MM*v(:,it))+(f*KM*u(:,it)))./((a*MM)+(b*KM))
    v(:,it+1)=g*(u(:,it+1)-u(:,it))-(h*v(:,it))
    a(:,it+1)=g*(v(:,it+1)-v(:,it))-(h*a(:,it))

end

[Geoff Hayes]

Laura - if I run the above code, I observe the error

 Error using  + 
 Matrix dimensions must agree.

 Error in *** (line 37)
    u(:,it+1)=((c*p1)+(d*p0)+(a1*MM*u(:,it))+(e*MM*v(:,it))+(f*KM*u(:,it)))./((a*MM)+(b*KM))

This is because you are adding a 4x1 matrices p1 and p0 to a 4x4 matrix MM. What are you expecting to occur at this line? What is the algorithm (reference) that you are using to develop your code?