Read cross-section file fetched from HITRAN-on-the-Web.
    The format of the file line must be as follows: 
      nu, coef
    Other lines are omitted.

def read_hotw(filename):
    """
    Read cross-section file fetched from HITRAN-on-the-Web.
    The format of the file line must be as follows: 
      nu, coef
    Other lines are omitted.
    """
    import sys
    f = open(filename,'r')
    nu = []
    coef = []
    for line in f:
        pars = line.split()
        try:
            nu.append(float(pars[0]))
            coef.append(float(pars[1]))
        except:
            if False:
                print(sys.exc_info())
            else:
                pass    
    return array(nu),array(coef)