function [xt,yt,zt]=solve_orbit(flag)

%*********************************
% ** % 畫星座軌道用
% flag為系統標志 gps:flag = 1;galileo: flag = 2; beidou:flag = 3 
% **********************************

X = [];
Y = [];
Z = []; 
if flag==1
    for t=0:50:43200
        [Xs,Ys,Zs]=gps_sat(t);
        X=[X,Xs(:,1)];
        Y=[Y,Ys(:,1)];
        Z=[Z,Zs(:,1)];
    end
end
if flag ==2
    for t=0:50:51840
        [Xs,Ys,Zs]=galileo_sat(t);
         X=[X,Xs(:,1)];
         Y=[Y,Ys(:,1)];
         Z=[Z,Zs(:,1)];
     end 
 end
 
xt=X';
yt=Y';
zt=Z';