For a fractal process with values  and 
, the correlation between these two values is given
 by the Brown function
also known as the Bachelier function, Lévy function, or Wiener function.
 
	    
	
    
For a fractal process with values  and 
, the correlation between these two values is given
 by the Brown function
also known as the Bachelier function, Lévy function, or Wiener function.
Weisstein, Eric W. "Brown Function." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/BrownFunction.html