def triangle_coordinates(i, j, k):
    """
    Computes coordinates of the constituent triangles of a triangulation for the
    simplex. These triangules are parallel to the lower axis on the lower side.

    Parameters
    ----------
    i,j,k: enumeration of the desired triangle

    Returns
    -------
    A numpy array of coordinates of the hexagon (unprojected)
    """
    return [(i, j, k), (i + 1, j, k - 1), (i, j + 1, k - 1)]
