'Index exceeds the number of array elements ' why this error is showing?

function dydt = my_ode_without_tld(i,y)
% tspan = i;                 %% Time span

%% Initial inputs
m1 = 10;             %% mass of the structure(kg)
k1 = 15;            %% stiffness of the structure(N/m)
c1 = 5;            %% damping of the structure(Ns/m)
A = 0.05;            %% Amplitude of ground displacement(m)
w = 6.981;           %% Input natural frequencycy(rad/s)

%% define frequency
w1 = sqrt(k1/m1);                  %% frequency of structure

%% define damping ratio of structure
r1 = c1/(2*m1*w1);

%% define ground acceleration
ugdd = -A*w^2*sin(w*i); 

%% Equation to solve
dydt = [y(4)
    (-ugdd-(2*r1*w1*y(4))-((w1)^2*y(3)))];
%% To run mass spring damper system
i = 0:0.01:20;
y = [0 0];

%% Solve using ode45

[tsol,ysol] = ode45('my_ode_without_tld', i, y,[1 0;0 1]);


%% plotting
plot(tsol,ysol(:,1))
xlabel('time(sec)')
ylabel('displacement(m)')
grid on
title('Displacement response of structure')
figure
plot(tsol,ysol(:,2))
xlabel('time(sec)')
ylabel('velocity(m/s)')
grid on
title('Velocity response of structure')

Answer 1

[KSSV]

This line:

dydt = [y(4)
    (-ugdd-(2*r1*w1*y(4))-((w1)^2*y(3)))];

expects y to be 1x4 vector, but your y is 1x2.

[RAJKUMAR SAHA]

Thank you

Answer 2

[VBBV]

I = 0:0.1:20;
y = [0 0];
%% Solve using ode45
[tsol,ysol] = ode45(@my_ode_without_tld,[0 10],[0;1]);
%% plotting
plot(tsol,ysol(:,1))
xlabel('time(sec)')
ylabel('displacement(m)')
grid on
title('Displacement response of structure')

figure
plot(tsol,ysol(:,2))
xlabel('time(sec)')
ylabel('velocity(m/s)')
grid on
title('Velocity response of structure')

function dydt = my_ode_without_tld(I,y)
% tspan = i;                 %% Time span
%% Initial inputs
m1 = 10;             %% mass of the structure(kg)
k1 = 15;            %% stiffness of the structure(N/m)
c1 = 5;            %% damping of the structure(Ns/m)
A = 0.05;            %% Amplitude of ground displacement(m)
w = 6.981;           %% Input natural frequencycy(rad/s)
%% define frequency
w1 = sqrt(k1/m1);                  %% frequency of structure
%% define damping ratio of structure
r1 = c1/(2*m1*w1);
%% define ground acceleration
ugdd = -A*w^2*sin(w*I); 
%% Equation to solve
dydt = [y(2) -ugdd-(2*r1*w1*y(2)-((w1)^2*y(1)))].';
%% To run mass spring damper system
end

[RAJKUMAR SAHA]

Thank you

[VBBV]

Thanks is accepting answer. :)