共查询到20条相似文献,搜索用时 93 毫秒
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《数学的实践与认识》2015,(20)
绝对值函数是一个非光滑函数,研究了绝对值函数的光滑逼近函数.给出了绝对值函数的上方一致光滑逼近函数和下方一致光滑逼近函数,分别研究了其性质,并通过图像展示了逼近效果. 相似文献
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研究negabent函数之间的关系,并利用bent-negabent函数构造出代数次数达到次最优的semibent-negabent函数. 相似文献
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考虑Simon反谱理论新方法中引入的A-函数,根据Weyl函数m关于A-函数的表示关系,利用广义函数和Fourier变换的方法求出A-函数关于Weyl函数m的反表示,该结论表明A-函数的本质是广义函数. 相似文献
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首先对现行教材中初等函数的定义提出了商讨意见,讨论了高等数学教材中出现的形式上的非初等函数与初等函数的关系,并通过一些有代表性的例子加以说明. 相似文献
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相关免疫函数的结构与构造 总被引:13,自引:0,他引:13
一、引言 在流密码学中,人们通常采用一个线性移位寄存器或多个线性移位寄存器再加一个滤波函数来作为流密钥序列生成器。非线性滤波函数的作用是为了提高流密钥序列的线性复杂度。Siegenthaler指出:如果滤波函数选择不当,破译者在仅知密文的情况下可以使用相关攻击的方法来攻击该体制。为了抵抗相关攻击的方法,Siegenthaler提出了相关免疫函数的概念,并给出开关函数是相关免疫函数的必要条件。肖国镇和J.L. 相似文献
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王志珍 《纯粹数学与应用数学》2015,(3):238-244
研究Fourier分析中的Dirichlet核函数、Fejr核函数和Poisson核函数,介绍优核的概念.证明Dirichlet核函数不是优核,Fejr核函数和Poisson核函数是优核. 相似文献
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《高校应用数学学报(A辑)》2021,36(2)
针对现实中经符号分析形成的区间函数型数据,提出时变距离函数概念,并将其应用于区间协方差计算.利用函数型主成分分析方法推导出相应的特征函数,提出了基于时变距离函数的多变量区间函数型主成分分析方法.通过实证证明:区间函数型主成分分析以区间化获取了更多信息,以函数化放松了假定,增加了可视化水平,能够有效解决区间函数型数据的特征提取和综合评价问题. 相似文献
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Serge B. Provost Edmund M. Rudiuk 《Annals of the Institute of Statistical Mathematics》1996,48(2):381-394
The exact density of the difference of two linear combinations of independent noncentral chi-square variables is obtained in terms of Whittaker's function and expressed in closed forms. Two distinct representations are required in order to cover all the possible cases. The corresponding expressions for the exact distribution function are also given. 相似文献
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In this paper, a variable-coefficient Jacobi elliptic function expansion method is proposed to seek more general exact solutions of nonlinear partial differential equations. Being concise and straightforward, this method is applied to the (2+1)-dimensional Nizhnik-Novikov-Vesselov equations. As a result, many new and more general exact non-travelling wave and coefficient function solutions are obtained including Jacobi elliptic function solutions, soliton-like solutions and trigonometric function solutions. To give more physical insights to the obtained solutions, we present graphically their representative structures by setting the arbitrary functions in the solutions as specific functions. 相似文献
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基于Lamé方程和新的Lamé函数,应用摄动方法和Jacobi椭圆函数展开法求解非线性演化方程,获得多种新的多级准确解.这些解在极限条件下可以退化为各种形武的孤波解. 相似文献
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In this paper, some new results on the exact penalty function method are presented. Simple optimality characterizations are given for the differentiable nonconvex optimization problems with both inequality and equality constraints via exact penalty function method. The equivalence between sets of optimal solutions in the original mathematical programming problem and its associated exact penalized optimization problem is established under suitable invexity assumption. Furthermore, the equivalence between a saddle point in the invex mathematical programming problem and an optimal point in its exact penalized optimization problem is also proved. 相似文献
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Some mathematical models in geophysics and graphic processing need to compute integrals with scattered data on the sphere. Thus cubature formula plays an important role in computing these spherical integrals. This paper is devoted to establishing an exact positive cubature formula for spherical basis function networks. The authors give an existence proof of the exact positive cubature formula for spherical basis function networks, and prove that the cubature points needed in the cubature formula are not larger than the number of the scattered data. 相似文献
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Josef Berger 《Mathematical Logic Quarterly》2005,51(2):201-205
We represent continuous functions on compact intervals by sequences of functions defined on finite sets of rational numbers. We call this an exact representation. This enables us to calculate the values of the function arbitrarily exactly, without roundoff errors. As an application we develop a procedure to transfer an exact representation of an increasing function into an exact representation of the corresponding inverse function. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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带等式约束的光滑优化问题的一类新的精确罚函数 总被引:1,自引:0,他引:1
罚函数方法是将约束优化问题转化为无约束优化问题的主要方法之一. 不包含目标函数和约束函数梯度信息的罚函数, 称为简单罚函数. 对传统精确罚函数而言, 如果它是简单的就一定是非光滑的; 如果它是光滑的, 就一定不是简单的. 针对等式约束优化问题, 提出一类新的简单罚函数, 该罚函数通过增加一个新的变量来控制罚项. 证明了此罚函数的光滑性和精确性, 并给出了一种解决等式约束优化问题的罚函数算法. 数值结果表明, 该算法对于求解等式约束优化问题是可行的. 相似文献