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Asymptotic semismoothness probabilities
 Mathematics of computation
, 1996
"... Abstract. We call an integer semismooth with respect to y and z if each of its prime factors is ≤ y, and all but one are ≤ z. Such numbers are useful in various factoring algorithms, including the quadratic sieve. Let G(α, β)bethe asymptotic probability that a random integer n is semismooth with res ..."
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Cited by 22 (1 self)
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Abstract. We call an integer semismooth with respect to y and z if each of its prime factors is ≤ y, and all but one are ≤ z. Such numbers are useful in various factoring algorithms, including the quadratic sieve. Let G(α, β)bethe asymptotic probability that a random integer n is semismooth with respect to n β and n α. We present new recurrence relations for G and related functions. We then give numerical methods for computing G,tablesofG, and estimates for the error incurred by this asymptotic approximation. 1.
Approximating the number of integers free of large prime factors
 Math. Comp
, 1997
"... Abstract. Define Ψ(x, y) to be the number of positive integers n ≤ x such that n has no prime divisor larger than y. We present a simple algorithm that log log x approximates Ψ(x, y) inO(y { log y + 1}) floating point operations. log log y This algorithm is based directly on a theorem of Hildebrand ..."
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Cited by 10 (1 self)
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Abstract. Define Ψ(x, y) to be the number of positive integers n ≤ x such that n has no prime divisor larger than y. We present a simple algorithm that log log x approximates Ψ(x, y) inO(y { log y + 1}) floating point operations. log log y This algorithm is based directly on a theorem of Hildebrand and Tenenbaum. We also present data which indicate that this algorithm is more accurate in practice than other known approximations, including the wellknown approximation Ψ(x, y) ≈ xρ(log x / log y), where ρ(u) is Dickman’s function. 1.
Asymptotic Semismoothness Probabilities
"... Abstract We call an integer semismooth with respect to y and z if each of its prime factors is ^ y, and all but one are ^ z. Such numbers are useful in various factoring algorithms, including the quadratic sieve. Let G(ff; fi) be the asymptotic probability that a random integer n is semismooth with ..."
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Abstract We call an integer semismooth with respect to y and z if each of its prime factors is ^ y, and all but one are ^ z. Such numbers are useful in various factoring algorithms, including the quadratic sieve. Let G(ff; fi) be the asymptotic probability that a random integer n is semismooth with respect to nfi and nff. We present new recurrence relations for G and related functions. We then give numerical methods for computing G, tables of G, and estimates for the error incurred by this asymptotic approximation.