def expand_quadratic_to_quartic(a):
    """
    This function gets a vector of coefficients from a quadratic fit and turns it
    into a vector of coeffients as from a quartic fit (extra coeffients are set to zero).
    """
    b=[a[0], a[1], a[2], 0.0, 0.0, 
    a[3], a[4], 0.0, 0.0,
    a[5], 0.0, 0.0, 0.0, 0.0,
    0.0]
    return b