Rounding-off Errors in Matrix Processes.

Oxford, Clarendon Press, 1948.

8vo. Bound in contemporary full calf with gilt lettering to spine. In "The Quarterly Journal of Mechanics and Applied Mathematics", Vol. 1, 1948. Previous owner's name written to front free-endpaper. Ver fine and clean. Pp. 287-380. [Entire volume: (4), 474 pp.].

First printing of this important paper in which Turing for the very first time introduced the concept of LU factorization or LU decomposition.
"Turing's paper was one of the earliest attempts to examine the error analysis of the various methods of solving linear equations and inverting matrices. His analysis was basically sound. The main importance of the paper was that it was published at the dawn of the modern computing era, and it gave indications of which methods were 'safe' when solving such problems on a computer". (Burgoyne, Collected Works of A M Turing).

"In 1945, [Turing] declined an offer of a Fellowship at King's [College, Cambridge] in favour of joining
the newly formed Mathematical Division at the National Physical Laboratory (NPL). His early work on computability, combined with his wartime experience in electronics, had fired him with an enthusiasm for working on the design of an electronic computer. \ethe machine he designed, which was called the Automatic Computing Engine (ACE) in recognition of Babbage's pioneering work, was characteristically original…
"While in the Mathematics Division of NPL, Turing became keenly interested in numerical analysis. His paper, "Rounding-off Errors in Matrix Processes", showed that the acute anxiety about the effect of rounding errors in Gaussian elimination was largely unjustified. This paper has been overshadowed to some extent by the von Neumann and Goldstine paper on matrix inversion, but it is a brilliant piece of work and would have repaid closer study at the time". ("Turing, Alan M." by James H. Wilkinson, p. 1803, in Encyclopedia of Computer Science, A. Ralston et al (eds.), 4th edition, Nature Publishing Group, 2000).

In linear algebra, LU decomposition factorizes a matrix as the product of a lower triangular matrix and an upper triangular matrix. LU decomposition is a key step in several fundamental numerical algorithms in linear algebra such as solving a system of linear equations, inverting a matrix, or computing the determinant of a matrix.

Not in Origins of Cyberspace nor The Erwin Tomash Library.

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