def gNFW_model_derivative(r3d_kpc, P0, r_p, slope_a=1.33, slope_b=4.13, slope_c=0.31):
    """
    Compute the derivative of the gNFW model (dP/dr)

    Parameters
    ----------
    - r3d_kpc (kpc): array of radius
    - P0 : normalization
    - r_p (kpc): characteristic radius parameter
    - sope_a : intermediate slope parameter
    - sope_b : outer slope parameter
    - sope_c : inner slope parameter

    Outputs
    --------
    - gNFW derivative model profile as a function of the input radius vector

    """

    t1 =  -P0 * (r3d_kpc / r_p)**(-slope_c)
    t2 = (1 + (r3d_kpc / r_p)**(slope_a))**((slope_c-slope_b-slope_a)/slope_a)
    t3 = (slope_b*(r3d_kpc/r_p)**slope_a + slope_c) / r3d_kpc
    
    return t1 * t2 * t3