def wrdvi(nir, red, alpha=0.1):
    """
    Compute Wide Dynamic Range Vegetation Index from red and NIR bands

        WRDVI = \\frac { \\alpha NIR - RED } {\\alpha  NIR + RED }

    :param nir:     Near-Infrared band
    :param red:     Red band
    :param alpha:   Weighting coefficient, usually in [0.1-0.2]
    :return:        WRDVI
    """
    return (alpha*nir - red) / (alpha*nir + red)