Mercurial > matrix-functions
view toolbox/gj.m @ 0:8f23314345f4 draft
Create local repository for matrix toolboxes. Step #0 done.
author | Antonio Pino Robles <data.script93@gmail.com> |
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date | Wed, 06 May 2015 14:56:53 +0200 |
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function x = gj(A, b, piv) %GJ Gauss-Jordan elimination to solve Ax = b. % x = GJ(A, b, PIV) solves Ax = b by Gauss-Jordan elimination, % where A is a square, nonsingular matrix. % PIV determines the form of pivoting: % PIV = 0: no pivoting, % PIV = 1 (default): partial pivoting. n = max(size(A)); if nargin < 3, piv = 1; end for k=1:n if piv % Partial pivoting (below the diagonal). [colmax, i] = max( abs(A(k:n, k)) ); i = k+i-1; if i ~= k A( [k, i], : ) = A( [i, k], : ); b( [k, i] ) = b( [i, k] ); end end irange = [1:k-1 k+1:n]; jrange = k:n; mult = A(irange,k)/A(k,k); % Multipliers. A(irange, jrange) = A(irange, jrange) - mult*A(k, jrange); b(irange) = b(irange) - mult*b(k); end x = diag(diag(A))\b;