def Concrete01Funct(fc, ec, fpcu, ecu, discretized_eps):
    """
    Function with the equation of the curve of the Concrete01 model.
    For more information, see Kent-Scott-Park concrete material object with
        degraded linear unloading/reloading stiffness according to the work of Karsan-Jirsa and no tensile strength.

    @param fc (float): Compressive concrete yield stress (negative).
    @param ec (float): Compressive concrete yield strain (negative).
    @param fpcu (float): Concrete crushing strength (negative).
    @param ecu (float): Concrete strain at crushing strength (negative).
    @param discretized_eps (float): Variable strain.

    @returns float: Stress in function of variable strain.
    """
    if discretized_eps > ec:
        eta = discretized_eps/ec;
        return fc*(2*eta-eta*eta);
    else:
        Ttangent = (fc-fpcu)/(ec-ecu)
        return fc + Ttangent*(discretized_eps-ec);