Vectors must be the same length.

Help!!! im trying to plot a graph. But its always tell me 'Vectors must be the same length.'

h=0.04; %step size

t=0.04:h:0.6; %time

y=[0.1560 0.0125 0.0850 0.2360 0.2450 0.0350 0.5610];%Displacement

v=diff(y)/h; %First derivative of y

a=diff(v)/h; %Second derivative of y

j=diff(a)/h; % Third derivative of y

%plot y vs t

plot(t,y,'LineWidth',2);

grid on

xlim([min(t) max(t)])

xlabel('t')

ylabel('y')

title('Plot of y vs. t')

Error using plot

Vectors must be the same length.

[Torsten]

What is the t vector that corresponds to the displacement vector ? It must have 7 elements.

Answer 1

[Star Strider]

Use the gradient function instead of diff and define ‘t’ based on ‘y’ —

% h=0.04; %step size
% t=0.04:h:0.6; %time
y=[0.1560 0.0125 0.0850 0.2360 0.2450 0.0350 0.5610];%Displacement
t = linspace(0.04, 0.6, numel(y));
h = t(2)-t(1)

h = 0.0933

v=gradient(y,h); %First derivative of y
a=gradient(v,h); %Second derivative of y
j=gradient(a,h); % Third derivative of y

%plot y vs t
figure
plot(t,y,'LineWidth',2);
grid on
xlim([min(t) max(t)])
xlabel('t')
ylabel('y')
title('Plot of y vs. t')

.