how to use loops and ode solver

I using two control inputs multiple times against certain condition to drive the states to zero in a certain order.i know that i need to use loops to achieve this but am totally lost.any help would be greatly appreciated. My code is as below.

function xdot=njc(t,x)
k1=1;
k2=1.5;
k3=1.5;
b1=0.5;
b2=0.6;
b3=0.75;
%Step 1. Drive the system to a nonzero equilibrium such that tan(x4) =/ 0 in finite time using
uu(1)=0;
uu(2)=-k1*(abs(x(4)-4)).^b1*sign(x(4)-4)-k2*(abs(x(5))).^b2*sign(x(5))-k3*(abs(x(6))).^b3*sign(x(6));
uu=[uu(1);uu(2)];

%Step 2. (After step 1 completes)Drive the x7 variable to zero while keeping x4 = 4 using
if x(4)==4  
   uu(1)=-1/tan(4)*(k1*(abs(x(7))).^b1*sign(x(7))+k2*(abs(x(8))).^b2*sign(x(8))+k3*(abs(x(9))).^b3*sign(x(9)));
   uu(2)=-k1*(abs(x(4)-4)).^b1*sign(x(4)-4)-k2*(abs(x(5))).^b2*sign(x(5))-k3*(abs(x(6))).^b3*sign(x(6));
   uu=[uu(1);uu(2)];
end

% % Step 3.(After step 2 completes) Drive the x4 variable to zero while keeping x7 = 0 using  
if x(7)<=0.0005 
   uu(1)=-k1*(abs(x(7))).^b1*sign(x(7))-k2*(abs(x(8))).^b2*sign(x(8))-k3*(abs(x(9))).^b3*sign(x(9));
   uu(2)=-k1*(abs(x(4))).^b1*sign(x(4))-k2*(abs(x(5))).^b2*sign(x(5))-k3*(abs(x(6))).^b3*sign(x(6));
   uu=[uu(1);uu(2)];
end

% % Step 4. (After step 3 completes)Drive the x1 variable to zero while keeping x4 = 0 using
if x(4)<=0.002  
   uu(1)=-k1*(abs(x(1))).^b1*sign(x(1))-k2*(abs(x(2))).^b2*sign(x(2))-k3*(abs(x(3))).^b3*sign(x(3));
   uu(2)=-k1*(abs(x(4))).^b1*sign(x(4))-k2*(abs(x(5))).^b2*sign(x(5))-k3*(abs(x(6))).^b3*sign(x(6));
   uu=[uu(1);uu(2)];
end

xdot(1)=x(2);
xdot(2)=x(3);
xdot(3)=uu(1);

xdot(4)=x(5);
xdot(5)=x(6);
xdot(6)=uu(2);

xdot(7)=x(8);
xdot(8)=x(9);
xdot(9)=uu(1)*tan(x(4));

xdot=xdot';