利用离散傅里叶变换的若干对称特性，证明实序列的离散傅里叶变换有下列对称特性： (1)Re[X(k)]=Re[X((-k)) N ]R N (k) (2)Im[X(k)]=-Im[X((-k))N]R N (k) (3)|X(k)|=|X((-k)) N |R N (k) (4)arg[X(k)]=-arg[X((-k)) N ]R N (k)