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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Computing 12 (1974), S. 223-246 
    ISSN: 1436-5057
    Keywords: Random numbers ; pseudorandom ; normal distribution ; gamma distribution ; bei distribution ; Poisson distribution ; binomial distribution ; simulation ; numerical analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Zur Erzeugung nicht-gleichverteilter Zufallszahlen braucht man Methoden, die gleichverteilte Zufallszahlen in Größen der gegebenen Verteilung transformieren. Es werden Transformationen untersucht, die Gamma-, Beta-, Poisson- oder Binomial-verteilte Zufallszahlen produzieren. Approximative Verfahren werden nicht behandelt. Die bisher bekannten Algorithmen sind langsam, wenn die Parameter der Verteilungen groß sind. Daher werden neue Methoden eingeführt, die diesen Nachteil weitgehend vermeiden. In allen Verfahren dürfen die Parameter beliebig und jedesmal neu gewählt werden. Für manche Transformationen werden normalverteilte Zufallszahlen als Zwischenschritt benötigt; die hierfür verwendete Methode ist ebenfalls angegeben.
    Notes: Abstract Accurate computer methods are evaluated which transform uniformly distributed random numbers into quantities that follow gamma, beta, Poisson, binomial and negative-binomial distributions. All algorithms are designed for variable parameters. The known convenient methods are slow when the parameters are large. Therefore new procedures are introduced which can cope efficiently with parameters of all sizes. Some algorithms require sampling from the normal distribution as an intermediate step. In the reported computer experiments the normal deviates were obtained from a recent method which is also described.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Computing 42 (1989), S. 159-170 
    ISSN: 1436-5057
    Keywords: Primary 65C10 ; Random numbers ; normal distribution ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Die effizientesten Algorithmen für Stichproben von der Standardnormalverteilung benötigen lange Listen von Konstanten. Die Größe dieser Tafeln wächst mit der verwendeten Präzision. Durch eine Anpassung der “Aliasmethode” von A.J. Walker an die Normalverteilung wird eine Stichprobenprozedur entwicklet, die nur drei feste Tafeln von je 128 Bytes braucht. Die neue Methode ist ebenso schnell wie ihre Konkurrenten und leichter zu implementieren.
    Notes: Abstract The most efficint algorithms for sampling from the standard normal distribution require long lists of constants. The size of these tables grows with the employed precision. By adapting A.J. Walker's “alias method” to the normal distribution a sampling procedure is developed which needs only three fixed tables of 128 bytes each. The new method is as fast as its competitors and easier to implement.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-601X
    Keywords: 25.20.Dc ; 25.85.Jg ; 27.90.+b
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The total photofission cross section σγ,F for235U and238U has been measured in the energy range 50≤E γ≤800 MeV at the 855 MeV Mainz Microtron MAMI using energy and time tagged photons (Glasgow Tagger) and a 4π arrangement of position sensitive fragment detectors. Besides the absolute photofission cross section σγF , which almost completely exhausts the total photon absorption cross section for these nuclei, fragment mass distributions in this energy domain were determined via time of flight techniques (TOF). The results for the total photofission cross sections σγ,F normalized to the atomic numberA for both isotopes coincide, and agree in theΔ-resonance region, within the systematic errors, with the socalled“Universal Curve” σγ,T /A of the total photon absorption cross section σγ,T . At higher energies the cross sections exhibit a smooth behaviour. In particular, it is shown for the first time that there isno resonance-like shape near the D13 resonance (at ≈710 MeV) as observed for the free proton. This complete suppression of the D13 resonance in complex nuclei is not yet understood on a microscopic level. The fragment mass distributions show a predominantly mass symmetric fission. However, contributions from mass asymmetric fission at some photon energies may give a hint of an increased mass asymmetric fission after the onset of the pion and two pion channels.
    Type of Medium: Electronic Resource
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