Getting an error message and don't know how to fix

I have code that looks like this

% The loop
for i=1:N-1
    v=diff(z);
    v(i+1) = v(i) + h*(((-g-k*(abs(v)).^p)*V)/m);
    z(i+1) = z(i)+h*v(i+1);
end

the error message has come up like this in the command window

Error in particle (line 24)
    v(i+1) = v(i) + h*(((-g-k*(abs(v)).^p)*V)/m);

No idea what ive done, its probably a really easy fix but im having a blonde moment. New to this stuff. Thanks :)

[the cyclist]

What is the complete error message?

[Holly Martin]

Unable to perform assignment because the left and right sides have a different number of elements.

Error in particle (line 24)
    v(i+1) = v(i) + h*(((-g-k*(abs(v)).^p)*V)/m);

Sorry- im so stupid sometimes haha

Answer 1

[the cyclist]

abs(v)

is a vector, so the right-hand side is a vector. You are trying to put that into one element of v on the left-hand side.

Maybe you meant

abs(v(i))

there?

[Holly Martin]

nice it worked thanks so much :)