def METHOD_NAME(rFluid=20, m=2):  # phi(rho)
    """Inverse Archie transformation function porosity(resistivity).
    # rFluid/rho = phi^m  ==> phi = (rFluid/rho)^(1/m) = (rho/rFluid)^(-1/m)
    See
    ---
    :py:mod:`pygimli.physics.petro.transFwdArchiePhi`
    """
    return pg.trans.TransPower(-1/m, rFluid)