In applied mathematics, symmetric successive over-relaxation (SSOR), is a preconditioner. If the original matrix can be split into diagonal, lower and upper triangular as A = D + L + L T {\displaystyle A=D+L+L^{\mathsf {T}}} then the SSOR preconditioner matrix is defined as
M = ( D + L ) D − 1 ( D + L ) T {\displaystyle M=(D+L)D^{-1}(D+L)^{\mathsf {T}}}
It can also be parametrised by ω {\displaystyle \omega } as follows.
M ( ω ) = ω 2 − ω ( 1 ω D + L ) D − 1 ( 1 ω D + L ) T {\displaystyle M(\omega )={\omega \over {2-\omega }}\left({1 \over \omega }D+L\right)D^{-1}\left({1 \over \omega }D+L\right)^{\mathsf {T}}}
See also Successive over-relaxation
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