Hi,
aakash here.
I have written the code below to solve the second order ODE using ODE45. There is an event condition in my code. Because of presence of this event condition, I am not (i dont know) able to use fixed time step in ODE45. Can somebody please help me with this. I request all to please help me to add the fixed time step in this code.
Waiting for the responses.
Thank you
~aakash
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
clc
clear all
close all
global k Th0 e m c t
%% Input parameters (Length (L), co-efficient of restitution (e), acceleration due to gravity (g))
e=0.9; m=1; c=0; k=246.46;
%% Initial condition
Thid = 8*40/(5*pi)^3; % position from where the mass is released
Thiv = 0; % inital velocity (at t=0)
Th0 = 0.05; % Position where the wall is there
tfi = 5; % time final time
%% ode45 (function call)
eta0=[Thid Thiv]; % Initial conditions
tspan=[0 tfi];
options = odeset('Events',@aakash_function);
t_vec = [];
eta_vec = [];
tcon=0;
ii=1;
while tcon<tfi %% to check whether final time is reached or not
tspan=[tcon tfi];
[t,eta] = ode45(@aakash_mass,tspan,eta0,options);
eta0=[eta(end,1) -(e*eta(end,2))]; %% modified inital conditions after impact
tcon=t(end,1);
t_vec = [t_vec;t];
eta_vec = [eta_vec;eta];
end
t_vec = [t_vec;t];
eta_vec = [eta_vec;eta];
%%
syms u5 x
u5 = sin(5*pi*x)*eta_vec(:,1)
%% Plot
% close all
for i = 1:length(u5)
fig = ezplot(u5(i))
set(fig,'Linewidth',1.5)
xlim([0 1])
ylim([-0.25 0.25])
grid on
title('only third mode')
pause(0.0000000000001)
end
