def ma_to_xy(m, a):
    """Convert (M, A) value back to read counts/densities of two samples.

    Parameters
    ----------
    m : float
        M value.
    a : float
        A vlaue.

    Returns
    -------
    x : float
        Converted read count/density in sample 1.
    y : float
        Converted read count/density in sample 2.
    """
    x = 2 ** (a + m / 2)
    y = 2 ** (a - m / 2)
    return x, y