Otherwise, the preconditioned matrix, which affects identification accuracy and robust noise immunity as well as robust ill-conditioning problem to some extent, is very important to the PCGM.

• 预优矩阵的选取对预处理共轭梯度法非常重要,因为它影响到预处理共轭梯度法的识别精度、抗噪性以及抗不适定性等关键问题。