What does some symbol in regular express mean?

 x = [1 0.3 -2 0.001 -0.00016, 582398, 3020];

regexp(num2str(x), '(?<=(^|\s+)[\-\.0]*)[1-9](?=\d*\.?\d*)', 'match')

What does these symbol '<' '=' mean?

How this expression work, first do what, then do what?

Answer 1

[Rolfe Dlugy-Hegwer]

(?<=expr) - Look behind from current position and test if expr is found.

For more information, see http://www.mathworks.com/help/techdoc/matlab_prog/f0-42649.html

[Oleg Komarov]

A small simplification (legit?)

regexp(num2str(x), '(?<=(^|\s+)[\-\.0]*)[1-9](?=[\d\.]*)', 'match')

[Walter Roberson]

Updated link: http://www.mathworks.com/help/matlab/matlab_prog/lookahead-assertions-in-regular-expressions.html