MATLAB: What does some symbol in regular express mean

benford's lawregexpregular expression

 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?

Best Answer

(?<=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
Related Question