This might be a really simple question, but I just didn't find an answer from anywhere.

I'm teaching linear algebra to myself and in my study material I came upon notation that I just don't understand. I can't find an explanation for it from my material and it is hard to find on the internet as well it seems.

Example:

$U=L((3,2,-6,4),(0,4,1,-5))$

What does the L() notation mean? U itself should be a subspace for ${R}^{4}$. I would assume that those are vectors within the L().

I'm teaching linear algebra to myself and in my study material I came upon notation that I just don't understand. I can't find an explanation for it from my material and it is hard to find on the internet as well it seems.

Example:

$U=L((3,2,-6,4),(0,4,1,-5))$

What does the L() notation mean? U itself should be a subspace for ${R}^{4}$. I would assume that those are vectors within the L().