Leslie01

% model parameters:
g = 9.81;      % gravity in m s^{-2}
v_t = 5.5;   % trim velocity in m s^{-1}   
L_D = 5.2;  % drag coefficient L/D


%%% set initial conditions %%%
v0 = v_t;     % start at the trim velocity (or add a delta)
theta0 = pi/12; % initial angle of trajectory
x0 = 0;     % horizotal position is arbitrary
y0 = 1000;  % initial altitude



% Establish differential equations (theta, v are unknowns)
%dv_dt = -g*sin(theta) - 1/L_D * g/v_t^2 .* v^2;
%dtheta_dt = -g/v*cos(theta) + g/v_t^2 .* v;
% tip: use ode23 function, ode45 function (create "myODE" function -> get v and theta)


% Break these next equations up into tiny time steps starting at t=0 (numerical intergation)
%x = v*cos(theta);
%y = v*sin(theta);


% u = matrix of vectors [v, theta, x, y]
% use Euler method: solve at initial coditions + time step, set that as new initial conditions, repeat


tstep = 1; % set time step for Euler method
t = [0:tstep:100]; % time vector (seconds)



[TOUT,YOUT] = ode23(dv_dt,[0 100],y0);