如:(1)-:显然z=1为单极,而 sin 0-01 T(z+ (3)I(z)= )I(2+2)I(z+n+1) z(2+1)z(x2+1)…(z+n) n→单极 (4)cgzl(=0,z=km?z=0? (5)sinlI k0,=0?z=∞03 0 1 : 1 , ? 1 1 1 0 2 | , 0? sin 0 ( 1) ( 2) ( 1) (3) ( ) , ( 1) ( 1) ( ) 4 | , ? ? (5 z z z z k z z z z z z e z z z z z n z z z z z z z n z n ctgz z k z p p ®¥ = = ¥ = = = ¥ - - ¥ - = = G + G + G + + G = = = + + ××× + = - ® = ¥ = = ¥ 如：（） 显然 为单极，而 （ ） 单极 （ ） 0 1 ) sin | , 0? ? z z z z z = = = ¥