X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/GMRES2stage.git/blobdiff_plain/acead508c1f820b919aa203c78668e5e645cc9b8..7d6625e2b26c8e17c8cf8fafc8fbed964dda513a:/paper.tex diff --git a/paper.tex b/paper.tex index bf9e767..ceffa3d 100644 --- a/paper.tex +++ b/paper.tex @@ -746,6 +746,26 @@ the convergence of GMRES($m$) for all $m$ under that assumption regarding $A$. \end{proposition} +We can now claim that, +\begin{proposition} +If $A$ is a positive real matrix and GMRES($m$) is used as solver, then the TSIRM algorithm is convergent. +\end{proposition} + +\begin{proof} +Let $r_k = b-Ax_k$, where $x_k$ is the approximation of the solution after the +$k$-th iterate of TSIRM. +We will prove that $r_k \rightarrow 0$ when $k \rightarrow +\infty$. + +Each step of the TSIRM algorithm \\ +$\min_{\alpha \in \mathbb{R}^s} ||b-R\alpha ||_2 = \min_{\alpha \in \mathbb{R}^s} ||b-AS\alpha ||_2$ + +$\begin{array}{ll} +& = \min_{x \in Vect\left(x_0, x_1, \hdots, x_{k-1} \right)} ||b-AS\alpha ||_2\\ +& \leqslant \min_{x \in Vect\left( S_{k-1} \right)} ||b-Ax ||_2\\ +& \leqslant ||b-Ax_{k-1}|| +\end{array}$ +\end{proof} + %%%********************************************************* %%%********************************************************* @@ -905,7 +925,7 @@ corresponds to 30*12, there are $max\_iter_{ls}$ which corresponds to 15. In Figure~\ref{fig:01}, the number of iterations per second corresponding to -Table~\ref{tab:01} is displayed. It can be noticed that the number of +Table~\ref{tab:03} is displayed. It can be noticed that the number of iterations per second of FMGRES is constant whereas it decreases with TSIRM with both preconditioners. This can be explained by the fact that when the number of cores increases the time for the least-squares minimization step also increases but, generally, @@ -1049,4 +1069,3 @@ Curie and Juqueen respectively based in France and Germany. % that's all folks \end{document} -