Nested function causes MATLAB crash (2011a)

The code is shown below. Do I have too many global variables? Am I missing something here?

function slslaunch()
    %dy = zeros(5,1);
    %units 
    tonforce = 9806.65; %convert to newtons
    tons = 1/0.00110231; %convert to kg

    %number of engines
    N_srb = 2;
    N_rs25 = 4;

    Isp_srb = 250;
    Isp_rs25 = 400; %this is sort of an average
    Isp_j2x = 451.5;

    T_srb = 1.428*tonforce*N_srb;
    T_rs25 = 830*tonforce; %includes 4 rs25's keyboard

    T_j2x = 11.2*tonforce;

    taub_srb = 128.4; %seconds
    taub_rs25 = 476; 
    taub_j2x = 377; 
    tau_orbit = 8000; %that sounds about like an orbit, right?

    mass_srb_tank = 100.39*tons*N_srb;
    mass_srb_fuel = 650.87*tons*N_srb;

    mass_rs25_tank = 89.38*tons;
    mass_rs25_fuel = 1002.5*tons;

    mass_j2x_tank = 22.063*tons;
    mass_j2x_fuel = 207.69*tons;

    %mass flow rates
    mdot_srb = mass_srb_fuel/ taub_srb;
    mdot_rs25 = mass_rs25_fuel/taub_rs25;
    mdot_j2x = mass_j2x_fuel/ taub_j2x;

    mass_interstage = 0*tons;

    mass_payload_fairing = 5.638*tons;

    mass_payload = 70*tons; 

    %initial mass
    M0 = mass_srb_tank + mass_srb_fuel + ...
    mass_rs25_tank + mass_rs25_fuel + ...
    mass_j2x_tank + mass_j2x_fuel + ...
    mass_interstage + mass_payload_fairing + mass_payload;

    %initial conditions
    g0 = 9.81; 
    h0 = 6378e3;
    V0 = 0;
    gam0 = (90-.01)/180*pi;
    x0 = 0;
    theta0 = 0;
    [t1,y1] = ode45(@launch,[0,taub_srb],[V0,M0,h0,gam0,theta0]);
    plot(t1,y1(:,1),'-',t1,y1(:,2),'-.',t1,y1(:,3),'.')

    % %y1 = V velocity 
    % y2 = M total mass 
    % y3 = h 
    % y4 = gamma 
    % y5 = theta
    function dy = launch(t,y)
    dy = zeros(5,1);
    g = g0*(h0/y(3))^2;
    dy(1) = ((T_srb + T_rs25)/y(2))-g*sin(y(4));         %(Fsrb + Frs25(main engine))
    dy(2) = mdot_srb+mdot_rs25;
    dy(3) = y(1)*sin(y(4));
    dy(4) = ((-g*cos(y(4))/y(1))+y(1)*cos(y(4))/y(3))*(y(4)/pi*180>80);   %controls gamma
    dy(5) = y(1)*cos(y(5))/y(3);
    [t1,y1] = ode45(@launch,[0,taub_srb],[V0,M0,h0,gam0,theta0]);
    plot(t1,y1(:,1),'-',t1,y1(:,2),'-.',t1,y1(:,3),'.')
    %[t2,y2] = ode45(@launch2,[taub_srb,t3],[y(;,end)]);
    end
end

%[t,y] = ode45(@launch,[0,taub_srb],[V0,M0,h0,gam0,theta0]);

%[t2,y2] = ode45(@launch2,[taub_srb,t3],[y(;,end)]);

%need to call ode45 three times for each seperation last output of previous
%ode45 will be initial condition of next ode45

Answer 1

[Titus Edelhofer]

Hi,

the problem is a recursion with calling ode45:

You call

[t1,y1] = ode45(@launch,[0,taub_srb],[V0,M0,h0,gam0,theta0]);

in the main function.

Inside function launch you call ode45 again:

[t1,y1] = ode45(@launch,[0,taub_srb],[V0,M0,h0,gam0,theta0]);

This leads to infinite recursion. Remove the ode45 and plot line from the launch function.

Titus

PS: MATLAB should not crash but give an error "Maximum recursion limit reached"...?