X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/kahina_paper1.git/blobdiff_plain/687362a4521c3b7fb4def6b81c7735feaccf5841..c5e1141650462fe452663bbf018f1c136914de28:/paper.tex?ds=sidebyside diff --git a/paper.tex b/paper.tex index 62ded30..02f98de 100644 --- a/paper.tex +++ b/paper.tex @@ -4,8 +4,10 @@ %%\usepackage[utf8]{inputenc} %%\usepackage[T1]{fontenc} %%\usepackage[french]{babel} +\usepackage{float} \usepackage{amsmath,amsfonts,amssymb} \usepackage[ruled,vlined]{algorithm2e} +%\usepackage[french,boxed,linesnumbered]{algorithm2e} \usepackage{array,multirow,makecell} \setcellgapes{1pt} \makegapedcells @@ -95,7 +97,7 @@ root finding of polynomials, high degree, iterative methods, Durant-Kerner, GPU, Polynomials are algebraic structures used in mathematics that capture physical phenomenons and that express the outcome in the form of a function of some unknown variable. Formally speaking, a polynomial $p(x)$ of degree \textit{n} having $n$ coefficients in the complex plane \textit{C} and zeros $\alpha_{i},\textit{i=1,...,n}$ %%\begin{center} \begin{equation} - {\Large p(x)=\sum{a_{i}x^{i}}=a_{n}\prod(x-\alpha_{i}),a_{0} a_{n}\neq 0}. + {\Large p(x)=\sum_{i=0}^{n}{a_{i}x^{i}}=a_{n}\prod_{i=1}^{n}(x-\alpha_{i}), a_{0} a_{n}\neq 0}. \end{equation} %%\end{center} @@ -328,7 +330,9 @@ Q(z_{k})=\exp\left( \ln (p(z_{k}))-\ln(p(z_{k}^{'}))+\ln \left( \sum_{k\neq j}^{n}\frac{1}{z_{k}-z_{j}}\right)\right). \end{equation} -This solution is applied when it is necessary ??? When ??? (SIDER) +This solution is applied when the root except the circle unit, represented by the radius $R$ evaluated as: + +$$R = \exp( \log(DBL\_MAX) / (2*n) )$$ where $DBL\_MAX$ stands for the maximum representable double value. \section{The implementation of simultaneous methods in a parallel computer} \label{secStateofArt} @@ -354,7 +358,7 @@ parallelism that can be suitably exploited by SIMD machines. Moreover, they have fast rate of convergence (quadratic for the Durand-Kerner and cubic for the Ehrlisch-Aberth). Various parallel algorithms reported for these methods can be found -in~\cite{Cosnard90, Freeman89,Freemanall90,,Jana99,Janall99}. +in~\cite{Cosnard90, Freeman89,Freemanall90,Jana99,Janall99}. Freeman and Bane~\cite{Freemanall90} presented two parallel algorithms on a local memory MIMD computer with the compute-to communication time ratio O(n). However, their algorithms require @@ -380,6 +384,8 @@ GPUs, which details are discussed in the sequel. \section {A CUDA parallel Ehrlisch-Aberth method} +In the following, we describe the parallel implementation of Ehrlisch-Aberth method on GPU +for solving high degree polynomials. First, the hardware and software of the GPUs are presented. Then, a CUDA parallel Ehrlisch-Aberth method are presented. \subsection{Background on the GPU architecture} A GPU is viewed as an accelerator for the data-parallel and @@ -478,7 +484,7 @@ $\Delta z_{max}$=c\;} ~\\ In this sequential algorithm, one CPU thread executes all the steps. Let us look to the $3^{rd}$ step i.e. the execution of the iterative function, 2 sub-steps are needed. The first sub-step \textit{save}s the solution vector of the previous iteration, the second sub-step \textit{update}s or computes the new values of the roots vector. -There exists two ways to execute the iterative function that we call a Jacobi one and a Gauss-Seidel one. With the Jacobi iteration, at iteration $k+1$ we need all the previous values $z^{(k)}_{i}$ to compute the new values $z^{(k+1)}_{i}$, taht is : +There exists two ways to execute the iterative function that we call a Jacobi one and a Gauss-Seidel one. With the Jacobi iteration, at iteration $k+1$ we need all the previous values $z^{(k)}_{i}$ to compute the new values $z^{(k+1)}_{i}$, that is : \begin{equation} H(i,z^{k+1})=\frac{p(z^{(k)}_{i})}{p'(z^{(k)}_{i})-p(z^{(k)}_{i})\sum^{n}_{j=1 j\neq i}\frac{1}{z^{(k)}_{i}-z^{(k)}_{j}}}, i=1,...,n. @@ -579,34 +585,29 @@ The last kernel verifies the convergence of the roots after each update of $Z^{( The kernels terminate it computations when all the roots converge. Finally, the solution of the root finding problem is copied back from GPU global memory to CPU memory. We use the communication functions of CUDA for the memory allocation in the GPU \verb=(cudaMalloc())= and for data transfers from the CPU memory to the GPU memory \verb=(cudaMemcpyHostToDevice)= or from GPU memory to CPU memory \verb=(cudaMemcpyDeviceToHost))=. %%HIER END MY REVISIONS (SIDER) -\subsection{Experimental study} +\section{Experimental study} -\subsubsection{Definition of the polynomial used} -We use a polynomial of the following form for which the -roots are distributed on 2 distinct circles: +\subsection{Definition of the polynomial used} +We study two forms of polynomials the sparse polynomials and the full polynomials: +\paragraph{Sparse polynomial}: in this following form, the roots are distributed on 2 distinct circles: \begin{equation} - \forall \alpha_{1} \alpha_{2} \in C,\forall n_{1},n_{2} \in N^{*}; P(z)= (z^{n^{1}}-\alpha_{1})(z^{n^{2}}-\alpha_{2}) + \forall \alpha_{1} \alpha_{2} \in C,\forall n_{1},n_{2} \in N^{*}; P(z)= (z^{n_{1}}-\alpha_{1})(z^{n_{2}}-\alpha_{2}) \end{equation} - This form makes it possible to associate roots having two different modules and thus to work on a polynomial constitute of four non zero terms. -\\ - An other form of the polynomial to obtain a full polynomial is: + +\paragraph{Full polynomial}: the second form used to obtain a full polynomial is: %%\begin{equation} %%\forall \alpha_{i} \in C,\forall n_{i}\in N^{*}; P(z)= \sum^{n}_{i=1}(z^{n^{i}}.a_{i}) %%\end{equation} \begin{equation} - {\Large \forall a_{i} \in C; p(x)=\sum^{n-1}_{i=1} a_{i}.x^{i}} + {\Large \forall a_{i} \in C, i\in N; p(x)=\sum^{n}_{i=0} a_{i}.x^{i}} \end{equation} -with this formula, we can have until \textit{n} non zero terms. - -\subsubsection{The study condition} -In order to have representative average values, for each -point of our curves we measured the roots finding of 10 -different polynomials. +with this form, we can have until \textit{n} non zero terms. +\subsection{The study condition} The our experiences results concern two parameters which are the polynomial degree and the execution time of our program to converge on the solution. The polynomial degree allows us @@ -614,12 +615,13 @@ to validate that our algorithm is powerful with high degree polynomials. The execution time remains the element-key which justifies our work of parallelization. For our tests we used a CPU Intel(R) Xeon(R) CPU -E5620@2.40GHz and a GPU Tesla C2070 (with 6 Go of ram) +E5620@2.40GHz and a GPU K40 (with 6 Go of ram). + -\subsubsection{Comparative study} +\subsection{Comparative study} We initially carried out the convergence of Aberth algorithm with various sizes of polynomial, in second we evaluate the influence of the size of the threads per block.... -\paragraph{Aberth algorithm on CPU and GPU} +\subsubsection{Aberth algorithm on CPU and GPU} %\begin{table}[!ht] % \centering @@ -638,7 +640,7 @@ We initially carried out the convergence of Aberth algorithm with various sizes % \label{tab:theConvergenceOfAberthAlgorithm} %\end{table} -\begin{figure}[htbp] +\begin{figure}[H] \centering \includegraphics[width=0.8\textwidth]{figures/Compar_EA_algorithm_CPU_GPU} \caption{Aberth algorithm on CPU and GPU} @@ -646,7 +648,7 @@ We initially carried out the convergence of Aberth algorithm with various sizes \end{figure} -\paragraph{The impact of the thread's number into the convergence of Aberth algorithm} +\subsubsection{The impact of the thread's number into the convergence of Aberth algorithm} %\begin{table}[!h] % \centering @@ -667,28 +669,30 @@ We initially carried out the convergence of Aberth algorithm with various sizes %\end{table} -\begin{figure}[htbp] +\begin{figure}[H] \centering \includegraphics[width=0.8\textwidth]{figures/influence_nb_threads} \caption{Influence of the number of threads on the execution times of different polynomials (sparse and full)} \label{fig:01} \end{figure} +\subsubsection{The impact of exp-log solution to compute very high degrees of polynomial} +\begin{figure}[H] +\centering + \includegraphics[width=0.8\textwidth]{figures/log_exp} +\caption{The impact of exp-log solution to compute very high degrees of polynomial.} +\label{fig:01} +\end{figure} + +\subsubsection{A comparative study between Aberth and Durand-kerner algorithm} -\paragraph{A comparative study between Aberth and Durand-kerner algorithm} -\begin{table}[htbp] - \centering - \begin{tabular} {|R{2cm}|L{2.5cm}|L{2.5cm}|L{1.5cm}|L{1.5cm}|} - \hline Polynomial's degrees & Aberth $T_{exe}$ & D-Kerner $T_{exe}$ & Aberth iteration & D-Kerner iteration\\ - \hline 5000 & 0.40 & 3.42 & 17 & 138 \\ - \hline 50000 & 3.92 & 385.266 & 17 & 823\\ - \hline 500000 & 497.109 & 4677.36 & 24 & 214\\ - \hline - \end{tabular} - \caption{Aberth algorithm compare to Durand-Kerner algorithm} - \label{tab:AberthAlgorithCompareToDurandKernerAlgorithm} -\end{table} +\begin{figure}[H] +\centering + \includegraphics[width=0.8\textwidth]{figures/EA_DK} +\caption{Ehrlisch-Aberth and Durand-Kerner algorithm on GPU} +\label{fig:01} +\end{figure} \bibliography{mybibfile}