How do I make this array index into a function of two other array indices?

I have the following arrays: cp, cx, theta, L

cp is a 71x1 array, cx is a 70x1 array, theta is a 70x1 array, L is a 70x1 array

I want to iterate:

for i=1:70
cx(i)=-L/(2)*(cp(i+1)+cp(i))*sin(theta(i));
end

I keep getting this error:

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

Error in example (line 40)

cx(i)=-L/(2)*(cp(i+1)+cp(i))*sin(theta(i));

How do I fix this error?

[Dyuman Joshi]

You indexed every array but L?

Answer 1

[Matt J]

Perhaps you meant to have this:

for i=1:70
 cx(i)=-L(i)/2*(cp(i+1)+cp(i))*sin(theta(i));
end

[Matt J]

If so, then BTW the one-line,loop-free way to do this is,

cx=-L.*movmean(cp,2,'End','discard').*sin(theta);