GENERALIZED CONJUGATE-GRADIENT ALGORITHM AND ITS APPLICATIONS TO SEISMIC TRACE INVERSION①
(Geophysical Institute Central South University of Technology,Changsha 410083, P. R. China)
Abstract: A novel generalized conjugate-gradient algorithm for complicated equations of seismic trace inverse problems, which is based on classical conjugate-gradient algorithm, has been put forward so as to improve the stability of seismic trace inversion, and to reduce inversion computation and memory resources needed. The algorithm brings high accuracy, fast operation speed and good ability of resisting ill-condition. In addition, by analysing sensitivity matrix according to the specific problem of seismic trace inversion, a new recursive algorithm which needs no sensitivity matrix is developed to save memory greatly. Furthermore, in the new algorithm, sensitivity matrix operation can be converted into convolution and correlation operations to make the whole recursion to be implemented completely by vector operation, which thus speeds recursion operation greatly.
Key words: seismic trace inversion conjugate-gradient algorithm accuracy stability operation speed