What does the order of unity mean in l' = l + αa?

[Warr]

While reading a physics text, I came across an equation
$$l' = l + \alpha\,a$$, where $$\alpha$$ is the order of unity. What exactly does this phrase mean (ie if I knew l and a, what would $$\alpha$$ be?)
thanks

 

[vanesch]

While reading a physics text, I came across an equation
$$l' = l + \alpha\,a$$, where $$\alpha$$ is the order of unity. What exactly does this phrase mean (ie if I knew l and a, what would $$\alpha$$ be?)
thanks

Guess what was written was " is of order unity", no ?

It means that $\alpha$ is a number that is not very far from 1, say 2 or 3 or so. Not 12352.0 and not 0.00002345.

 

[Warr]

Yes, that is exactly what was written.
so if I am doing a calculation based on this statement, what could I give the value of l' to be assuming I knew the precise values of l and a?