ROCEWEA. matrix cosine
Title of paper:
    
        
            An algorithm based on adaptive filtering technique for the computation of large-scale matrix cosine being
                nearly sparse
        
    
Authors: Jiqiang Hu, Feng, Wu, Li Zhu, Yuelin Zhao, Wanxie Zhong
    The scaling-squaring method (SSM) s for computing the matrix cosine function has been developed for many years, but
    it is not applicable for the large-scale sparse matrix as it requires more memory and higher computation cost than
    they are actually needed.
    In this paper, we analyze the localization phenomenon of the matrix cosine by two concepts, the real-bandwidth and
    the epsilon-bandwidth, and find that for the matrix cosine, there exists an approximate sparse matrix cosine under
    the given error tolerance. The existence of this approximate sparse matrix cosine provides the mathematical basis
    for the application of filtering technique. Then, a new algorithm which combines the filtering technique with the
    SSM is proposed. The error changes in the iterative process of the proposed algorithm is discussed, and an adaptive
    filtering threshold based on the error analysis is given.
    Numerical experiments show that the new algorithm can greatly improve the computational efficiency of large-scale
    sparse matrix cosine function with high accuracy and less memory, compared with several existing numerical
    algorithms.
Code
    Type: MATLAB code 
    
        File: cosfilt.rar
    
    Contents: 
    The algorithm proposed in this article: cosfilt.m; 
    And the filtration algorithm ‘filtoutA4.m’ proposed in ‘High-performance computation of large sparse matrix
    exponential’.
    27 test matrices: A1.mat ~ A27.mat
    
    
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