f(z) = (1-e^(2z))/z^4.易见f(z)在复平面上只有唯一极点z = 0.由幂级数展开e^z = 1+z+z²/2+z³/6+...,可算得e^(2z) = 1+2z+2z²+4z³/3+...,进而得到z = 0处Laurent展开f(z) = (1-e^(2z))/z^4 = 1/...