def write_sq_normal(fname,qs,sq):
    """
    Write S(Q) data in normal, gnuplot-readable format.
    """
    nd = len(qs)
    with open(fname,'w') as f:
        f.write('# S(Q) computed in rdf.py\n')
        f.write('# Q,             S(Q)\n')
        for i in range(nd):
            f.write(' {0:10.4f}  {1:10.5f}\n'.format(qs[i],sq[i]))
    return None