function xplp=fh(t,x)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%       
% function xplp=fh(t,x)
% Right hand side to the differential equations governing
% the optimal orbit transfer in the omputer exercise for the  
% course Optimal Control 5B1872
%
% x = x(1:3)
% lambda = x(4:6)

global c1 c2 c3 

x1=x(1);
x2=x(2);
x3=x(3);
l1=x(4);        %lambda1
l2=x(5);        %lambda2
l3=x(6);        %lambda3

global c1 c2 c3 %constants

% Control - thrust angle
% Antiparallell to (l2, c3*l3)
 
nrm = sqrt(l2^2+(c3*l3)^2);
if nrm ~= 0
sinu=-l2/nrm;
cosu=-c3*l3/nrm;
else
sinu = 0;
cosu = 1;
end


% Fuel consumption -> Mass decreasing with time 
mt=(1/c1-c2*c3*t);

% xplp: xDotLambdaDot vector
% WRITE STUFF BELOW:	
xplp=[(?)	;	% x1dot
     (?)	;	% x2dot
     (?) 	;	% x3dot
     (?)	;	% l1dot
     (?)	;	% l2dot
     (?)];		% l3dot
     
     


