KL2AB is the jEllipse module of jLab.

 KL2AB  Converts ellipse parameters Kappa and Lambda to A and B.
 
    [A,B]=KL2AB(K,L) converts ellipse amplitude K and ellipse 
    parameter L to semi-major and semi-minor axes A and B.
 
    A and B are related to K and L by
 
          A = SIGN(L) * K * SQRT(1 + ABS(L))
          B = SIGN(L) * K * SQRT(1 - ABS(L))
 
    as discussed in Lilly and Gascard (2006).  
  
    K and L are either arrays of the same size, or one may be an array
    and one may be a scalar.
 
    Usage: [a,b]=kl2ab(kappa,lambda)
    __________________________________________________________________
    This is part of JLAB --- type 'help jlab' for more information
    (C) 2007--2009 J.M. Lilly --- type 'help jlab_license' for details