Add functions core.preconditioners.{jacobi,ssor}

+core/+preconditioners/jacobi.m

@@ -0,0 +1,14 @@
+function prec = jacobi ( A )
+%
+% prec = jacobi ( A )
+%
+% Computes the Jacobi preconditioner for the matrix A of a system Ax = b.
+%
+
+ arguments
+ A (:,:)
+ end
+
+ prec = diag ( diag ( A ) ) \ eye ( size ( A ) ) ;
+
+end % function

+core/+preconditioners/ssor.m

@@ -0,0 +1,32 @@
+function prec = ssor ( A, kwargs )
+%
+% prec = ssor ( A, kwargs )
+%
+% Computes the SSOR preconditioner for the matrix A of a system Ax = b.
+%
+% kwargs:
+%
+% - coeff = 1
+%
+% The preconditioner constant used in the computation. The default value of 1
+% corresponds to the Gauss--Seidel preconditioner.
+%
+
+ arguments
+ A (:,:)
+ kwargs.coeff (1,1) double { mustBeInRange(kwargs.coeff, 0, 2) } = 1
+ end
+
+ L = tril ( A ) ;
+
+ U = triu ( A ) ;
+
+ D = diag ( diag ( A ) ) ;
+
+ invD = D \ eye ( size ( D ) ) ;
+
+ coeff = kwargs.coeff ;
+
+ prec = ( D + coeff * L ) * invD * ( D + coeff * U ) ;
+
+end % function