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4.6 CSAMAT

Aim:

Determine a preconditioning matrix by selecting coefficients from matrix A, already factorized and stored in a MUA data structure. The resulting preconditioning matrix is stored in a AMAT structure. It corresponds to extracting the significant coefficients, according to the criterion:

This procedure enables us to compute a preconditioning matrix efficiently, but necessitates the assembly of matrix A in skyline form in secondary memory. This technique is interesting when numerous linear systems need to be solved using the same matrix. To use this module, please consult section 2.1.6.