def rtvicore(b3, b5, b8):
    """
    Red-edge Triangular Vegetation Index (Chen et al., 2010).

    .. math:: RTVIcore = 100 * (b8 - b5) - 10 * (b8 - b3)

    :param b3: Green.
    :type b3: numpy.ndarray or float
    :param b5: Red-edge 1.
    :type b5: numpy.ndarray or float
    :param b8: NIR.
    :type b8: numpy.ndarray or float

    :returns RTVIcore: Index value

    .. Tip::

       Chen, P. F., Nicolas, T., Wang, J. H., Philippe, V., Huang, W. J., Li, \
       B. G. 2010. New index for crop canopy fresh biomass estimation. \
       Spectroscopy and Spectral Analysis 30(2), 512-517. \
       10.3964/j.issn.1000-0593(2010)02-0512-06.
    """

    RTVIcore = 100 * (b8 - b5) - 10 * (b8 - b3)
    return RTVIcore