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本文用代数工具对n元二次式的极值作一讨论,给出极值的判定和求出极值的一个一般方法。 首先,一般的n元二次多项式形如 相似文献
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<正> 在研究多元函数的极值问题中,我们经常会遇到多元二次齐次函数,本文根据这类函数的结构特点,应用实二次型的正定性,给出判定极值的一个简单方法。设实n元二次齐次函数的矩阵表达式为 相似文献
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针对多元函数稳定点处二阶偏导数全为0的情况,提出了有效的极值判别法.定义了广义n维方阵、n次型及其正定性;提出了更具普遍意义的极值充分条件;得到了利用n次型的正定性判断n元函数极值的方法并举例验证了结论的正确性和有效性. 相似文献
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定义.D是n维欧氏室空中一个点集,n≥2,f(x_1,x_2,…,x_n)是定义在D上的一个n元函数。如果f在D上极值存在,并且位于诸变量相等时,那末,称f在D上具有等变量极值。定理. 设f(x_1,x_2,…,x_n)(n≥3)是定义在D上的一个n元函数。如果f(x_1,x_2,…,x_n)在D上具有极大(小)值,且任意固定 相似文献
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本刊文[1]利用平均值不等式,给出了求三次函数极值的一个初等方法,读后得益非浅,颇受启发.作为对该文的一点补充,笔者拟给出三次函数极值的另一个简便的初等求法。求一般三次函数的极值,都可以归结为求 相似文献
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本文给出并严格证明了"一元实系数偶数(≥2)次多项式函数有极值"这一定理,并对多项式函数的次数及最高次项系数的符号与极值点的关系进行了归纳. 相似文献
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H. Ferreira 《Statistics & probability letters》2011,81(5):586-591
We extend the characterizations given by Takahashi (1988) for the independence and the total dependence of the univariate marginals of a multivariate extreme value distribution to its multivariate marginals. We also deal with the problem of how to measure the strength of the dependence among multivariate extremes. By presenting new definitions for the extremal coefficient, we propose measures that summarize the dependence between two multivariate extreme value distributions and preserve the main properties of the known bivariate coefficient for two univariate extreme value distributions. Finally, we illustrate these contributions to model the dependence among multivariate marginals with examples. 相似文献
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René Michel 《Extremes》2007,10(3):83-107
The investigation of multivariate generalized Pareto distributions (GPDs) has begun only recently. For further progress with
these distributions simulation methods are an important part. We describe several methods of simulating GPDs, beginning with
an efficient method for the logistic GPD. The algorithm is based on the Shi transformation, which was already used for the
simulation of multivariate extreme value distributions (EVDs) of logistic type. In the sequel another algorithm is presented
simulating a broader class of GPDs. Due to its numerical complexity it is only practicably applicable in low dimensions. A
method is given to generate unconditional GPD random vectors from conditionally GPD distributed random vectors. A short application
of the simulation methods in the analysis of a real hydrological data set concludes the article. The simulation algorithms
are available on the author’s home page .
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本文对二元函数极值的充分条件作了进一步的讨论 ,得到了 AC-B2 =0时 ,二元函数极值判定的充分条件 相似文献
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本把Botsko于1986年首先提出的关于多元函数f(x)于点x^#取极小值的一阶充分条件加以改进,并推广到具有等式约束的情形。得到的若干成果将为解决经济优化问题提供方便。 相似文献
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Joe H. 《Journal of multivariate analysis》1993,46(2)
Parametric families of continuous bivariate distributions with given margins that include independence and perfect positive dependence are compared on the basis on some important properties. Since many such families exist, the comparisons are helpful for deciding on suitable models for multivariate data. The study of the properties has motivation from applications in extreme value inference. One property considered for bivariate families is whether they extend to multivariate families, and extensions are given when possible. Several new bivariate and multivariate families are included and some open research problems in the area of multivariate families are mentioned. 相似文献
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Seokhoon Yun 《Journal of multivariate analysis》1997,63(2):277-295
The paper gives sufficient conditions for domains of attraction of multivariate extreme value distributions. Under the assumption of absolute continuity of a multivariate distribution, the criteria enable one to examine, by using limits of some rescaled conditional densities, whether the distribution belongs to the domain of attraction of some multivariate extreme value distribution. If this is the case, the criteria also determine how to construct such an extreme value distribution. Unlike the criterion given by de Haan and Resnick [1987,Stochastic Process. Appl.2583–93], the criteria are easily applicable even when the marginal tails are not Pareto-like. 相似文献
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