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- George E. Collins, Alkiviadis G. Akritas
- SYMSACC
- 1976

Uspensky's 1948 book on the theory of equations presents an algorithm, based on Descartes' rule of signs, for isolating the real roots of a squarefree polynomial with real coefficients. Programmed in SAC-1 and applied to several classes of polynomials with integer coefficients, Uspensky's method proves to be a strong competitor of the recently discovered… (More)

- Alkiviadis G. Akritas
- Computing
- 1980

Given an m×n matrix A, with m ≥ n, the four subspaces associated with it are shown in Fig. 1 (see [1]). Fig. 1. The row spaces and the nullspaces of A and A T ; a 1 through a n and h 1 through h m are abbreviations of the alignerframe and hangerframe vectors respectively (see [2]). The Fundamental Theorem of Linear Algebra tells us that N (A) is the… (More)

- Alkiviadis G. Akritas
- SYMSAC
- 1986

In this paper an attempt is made to correct the misconception of several authors [1] that there exists a method by Upensky (based on Vincent's theorem) for the isolation of the real roots of a polynomial equation with rational coefficients. Despite Uspensky's claim, in the preface of his book [2], that he invented this method, we show that what Upensky… (More)

- Alkiviadis G. Akritas, Gennadi I. Malaschonok
- Mathematics and Computers in Simulation
- 2004

Let A be an m × n matrix with m ≥ n. Then one form of the singular-value decomposition of A is A = U T ΣV, where U and V are orthogonal and Σ is square diagonal. That is, UU T = I rank(A) , V V T = I rank(A) , U is rank(A) × m, V is rank(A) × n and Σ = σ 1 0 · · · 0 0 0 σ 2 · · · 0 0. .. 0 0 · · · σ rank(A)−1 0 0 0 · · · 0 σ rank(A) … (More)

In this paper we compare two real root isolation methods using Descartes' Rule of Signs: the Interval Bisection method, and the Continued Fractions method. We present some time-saving improvements to both methods. Comparing computation times we conclude that the Continued Fractions method works much faster save for the case of very many very large roots.

- Alkiviadis G. Akritas, Stylianos D. Danielopoulos
- Computing
- 1980

- Alkiviadis G. Akritas
- ACM-SE 16
- 1978

A new method is presented for the isolation of the real roots of a given integral, univariate, square-free polynomial P. This method is based on Vincent's theorem and only uses: (i) Descartes' rule of signs, and (ii) transformations of the form x = a<inf>1</inf> + 1/x′, x′ = a<inf>2</inf> + 1/x″, x″ = a<inf>3</inf> + 1/x‴,… (More)

We present an implementation of the Continued Fractions (CF) real root isolation method using a recently developed upper bound on the positive values of the roots of polynomials. Empirical results presented in this paper verify that this implementation makes the CF method always faster than the Vincent-Collins-Akritas bisection method 3 , or any of its… (More)