Given a nxn nonsingular linear system Ax=b, we prove that thesolution x can be computed in parallel time ranging from Omega(logn) to O(log^2 n), provided that the condition number, c(A), of A isbounded by a polynomial in n. In particular, if c(A) = O(1), a timebound O(log n) is achieved. To obtain this result, we reduce thecomputation of x to repeated matrix squaring and prove that a numberof steps independent of n is sufficient to approximate x up to arelative error 2^–d, d=O(1). This algorithm has both theoretical andpractical interest, achieving the same bound of previously publishedparallel solvers, but being far more simple.
Repeated Matrix Squaring for the Parallel Solution of Linear Systems / B., Codenotti; Leoncini, Mauro; G., Resta. - STAMPA. - 605:(1992), pp. 725-732. (Intervento presentato al convegno International Conference Parallel ARchitectures and Languages Europe, PARLE 92 tenutosi a Paris, France nel June 15-18, 1992).
Repeated Matrix Squaring for the Parallel Solution of Linear Systems
LEONCINI, Mauro;
1992
Abstract
Given a nxn nonsingular linear system Ax=b, we prove that thesolution x can be computed in parallel time ranging from Omega(logn) to O(log^2 n), provided that the condition number, c(A), of A isbounded by a polynomial in n. In particular, if c(A) = O(1), a timebound O(log n) is achieved. To obtain this result, we reduce thecomputation of x to repeated matrix squaring and prove that a numberof steps independent of n is sufficient to approximate x up to arelative error 2^–d, d=O(1). This algorithm has both theoretical andpractical interest, achieving the same bound of previously publishedparallel solvers, but being far more simple.
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