From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 6095 invoked by alias); 29 Jan 2004 15:14:55 -0000 Mailing-List: contact gsl-discuss-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gsl-discuss-owner@sources.redhat.com Received: (qmail 9312 invoked from network); 29 Jan 2004 14:39:38 -0000 To: gsl-discuss@sources.redhat.com From: Subject: linear system problem Date: Thu, 29 Jan 2004 15:14:00 -0000 X-Posting-IP: 80.28.186.152 X-SW-Source: 2004-q1/txt/msg00033.txt.bz2 Message-ID: <20040129151400.e-e1DadAbBFpOPF_uQH9INWcCCu6G140EPOYHQYcZw8@z> Dear sirs, I am a student of Computer Engineering at Madrid University, Spain. First of all I want to congratulate you for the very useful "Scientific Library GSL" you have. The matter that concerns me is: I need to solve the linear system A x = b, where A is a rectangular M-by-N matrix, and M > N. Looking the functions of the library, I decided to use de QR descomposition. Before any calculation, I create the A matrix and b vector view, the 'x' and 'tau' vectors of N size, and the 'residual' vector of M size. First, I call the function gsl_linalg_QR_decomp() with the matrix A and the vector 'tau'. Then I call the gsl_linalg_QR_lssolve() function with the arguments A (with the QR descomposition created by the previous function), tau, b, x, and residual, to find the solution to the linear system. I´m almost sure that these equations are correct but the solution is not. What should I expect ? My question is; am I either using the right functions, or puting them in the right order? Shall I use another kind of descomposition? Thank you very much for your cooperation Sincerely, Jaime Carsi Jaudenes. --------------------------------------------- This message was sent using Endymion MailMan. http://www.endymion.com/products/mailman/