def incid_ref_press(p_d, gamma_inc) ->'p_inc':
    """Calculate DNVGL-ST-F101 «incidental reference pressure». 

    :param p_d: $p_d$ design pressure
    :param gamma_inc: $\\gamma_{inc}$ incidental to design pressure ratio
    :returns: p_inc: $p_{inc}$ incidental reference pressure

    Reference:
    DNVGL-ST-F101 (2017-12) 
        eq:4.3 sec:4.2.2.2 page:67 p_{inc}

    Example:    
    >>> incid_ref_press(100e5, 1.1)
    11000000.0
    """
    return p_d * gamma_inc
