unknown code- understand it up to the for loop but am lost from there. Can anyone lend a hand? thanks.

dat=load('data.dat')
a=dat(:,1)
b=dat(:,2)
s=size(a)
s=s(1)
out=zeros(s,1)
for n=1:s
	out(n)=(b(n+1)-b(n-1))/(a(n+1)-a(n-1))
end
c=[a out]

Answer 1

[Thiago Henrique Gomes Lobato]

What the code was supposed to be? it looks like the variable out is suppose to be the numerical derivative of b with respect to a. If the distance between each "a" is uniform and increasing, than this is the central scheme for 1st order differentiation with 2nd order accuracy and the line describe basically .

[Josh Williams]

not too sure what the code is supposed to be, thats what i have been tasked to find out. I can see now where your coming from with the derivations though. what does the line s=s(1) do?

[Thiago Henrique Gomes Lobato]

Size returns two values, so s(1) saves the first dimension in order to perform the loop and size assignment. It would be the same if you did:

s=size(a,1);
out=zeros(s,1);
...