Fast solution of linear systems by wavelet transform

We develop in this study a wavelet transform method to apply to the flux reconstruction problem in reactor analysis. When we reconstruct pinwise heterogeneous flux by iterative methods, a difficulty arises due to the near singularity of the matrix as the mesh size becomes finer. Here we suggest a wavelet transform to lower the spectral radius of the near singular matrix and thus to converge by a standard iterative scheme. We find that the spectral radius becomes smaller than one after the wavelet transform is performed on sample problems