def dB2power(x, db_gain=0):
    """
    Transform data in dB scale into power (amplitude²)
    A gain (db_gain) could be added at the end.    

    Parameters
    ----------
    x : array-like or scalar
        data in dB to rescale in power 
    db_gain : scalar, optional, default is 0
        Gain that was added to the result 
        --> 10*log10(x) + db_gain

    Returns
    -------
    y : array-like or scalar
        output in power unit

    Examples
    --------
    >>> a = np.array([ 0.        ,  6.02059991,  9.54242509, 12.04119983, 13.97940009])
    >>> maad.util.dB2power(a)
        array([ 1.        ,  4.        ,  8.99999999, 16.00000001, 25.00000002])        
    """
    y = 10**((x - db_gain)/10)

    return y