why do i receive this error?

clc, clear

t=0:1:20

S(t)=2*t.^2

V(t)=diff(S(t));

a(t)=diff(V(t));

subplot(1,3,1)

plot(t,S(t))

title('Position vs. Time')

xlabel('Time in seconds')

ylabel('Position in meters')

subplot(1,3,2)

plot(t,V(t))

title('Velocity vs. Time')

xlabel('Time in seconds')

ylabel('Velocity in m/s')

subplot(1,3,3)

plot(t,a(t))

title('Acceleration vs. Time')

xlabel('Time in seconds')

ylabel('Acceleration in m/s^2')

This is my code but it shows:

Array indices must be positive integers or logical values.

Error in (line 4)

S(t)=2*t.^2

i think its something related to the time array.

Answer 1

[Dyuman Joshi]

The error occurs because 0 can not be an index in MATLAB (Indexing starts from 1) and you tried to initialize the variable S (V and T as well) with 0

What you are trying to do is quite different than the code you wrote.

This should give what you are looking for -

syms S(t)
S(t)=2*t.^2;
V(t)=diff(S(t));
a(t)=diff(V(t));
figure
subplot(1,3,1)
fplot(t,S(t),[0 20])
title('Position vs. Time')
xlabel('Time in seconds')
ylabel('Position in meters')
subplot(1,3,2)
fplot(t,V(t),[0 20])
title('Velocity vs. Time')
xlabel('Time in seconds')
ylabel('Velocity in m/s')
subplot(1,3,3)
fplot(t,a(t),[0 20])
title('Acceleration vs. Time')
xlabel('Time in seconds')
ylabel('Acceleration in m/s^2')

[shamma aljaberi]

Thank you! it worked