Plotting differential equations, need help

y = diff(sin(2*pi*t))./diff(t); 
plot(t,y)

Remember diff() shortens the length of your vector by one so you will need to define a new time vector to plot against. ---- how do i do this?

thank you

Answer 1

[Yu Jiang]

plot(t(2:end),y)

[Andrew]

yeah works for sin(), however when you try to do it for t^2. come sup with error.

[Geoff Hayes]

What is the error, and the line(s) of code that you are using?

[Andrew]

using your fix for the plot(t(2:end),y), as plot(t,y) doesn't work

Error using diff
Difference order N must be a positive integer scalar.

[Andrew]

   y=diff(t,t);
   plot(y,t)

returning an error

[Yu Jiang]

what is the t vector? What is the expected result from y=diff(t,t)?? This is different from you original post.

I tried the following on my machine, and it worked

t = linspace(-10,10,100);
y = diff(sin(2*pi*t))./diff(t); 
plot(t(2:end),y)

[Andrew]

yeah it works, but when u integrate that technique into a different equation, it triggers an error.

[Andrew]

its ok, i fixed it. thanks for your help sir.

[Yu Jiang]

You are welcome.