Forward euler - a system of 4 ode

I am trying to program in matlab a code to excute forward euler. I have these DE:

x'(t)=u     

y'(t)=v

u'(t)=-kx*u*V

v'(t)=-g-ky(v*V)

where kx,ky and g are constants and V=sqrt(u^2+v^2)

The first thing that I have done is that I have called:

w_1'=x'

w_2'=y'

w_3'=u'

w_4'=v'
so I can express the 4 system of DE in terms of w:

w_3

w_4

-kx*w_3+sqrt((w_3)^2+(w_4)^2)

-g-ky*w_4*(sqrt((w_3)^2+(w_4)^2)

Now to the MATLAB code:

x0 = 0;    

N = 16000;   

h = 2./N;  

kx=0.020;

ky=0.065;

g=9.81;

x_i =  [0 ; 1.5; 19*cos(45); 19*sin(45)];  % initialconditons
for i = 1:N;
    x_n = x0 + (i-1).*h;

     diff=[x_n;x_n;-kx*(x_n*sqrt((x_n).^2+(x_n).^2));-g-ky*x_n*sqrt((x_n).^2+(x_n).^2)];

     e= x_i + h.*diff; %euluerforward

end

I am not sure if I have done it right, because my answers are almost similiar to my initialconditions?