def HI_1215(L_1197, L_1216, L_1235):
    """
        1215 Hydrocarbon Index ==================================================
            Convert numpy arrays of radiance data to a 1215 hydrocarbon index map

        Inputs ==================================================================
            L_1197 : At-sensor radiance at 1197 nm wavelength (numpy array)
            L_1216 : At-sensor radiance at 1216 nm wavelength (numpy array)
            L_1235 : At-sensor radiance at 1235 nm wavelength (numpy array)

        Returns =================================================================
            1215 Hydrocarbon Index Map

    """
    return 1.2 * L_1197 - 1.1 * L_1216 + 0.5 * (1.2 * L_1235 - L_1197 * 1.1)
