一种带参数的有理三次样条函数及其应用

构造了一种带参数的有理三次样条函数,它是标准三次样条函数的推广.选择合适的参数,该样条曲线比标准三次插值曲线更加逼近被插值曲线.参数还能局部调节曲线的形状,这给约束控制带来了方便.研究了该种插值曲线的区域控制问题.给出了将其约束于给定的二次曲线之上、之下或之间的充分条件.文中给出了两个数值例子.     

基于函数值的线性有理插值样条的区域控制

将插值曲线约束于给定的区域之内是插值与逼近的一个重要内容.本文讨论了一种带形状参数的线性有理插值样条的区域控制问题.给出将插值曲线约束于给定的折线及抛物线之上、之下或之间的条件.数值实例表明本文给出的条件在曲线设计中是有效的.     

加权有理三次插值的逼近性质及其应用

利用带导数和不带导数的分母为线性的有理三次插值样条构造了一类加权有理三次插值函数,利用这种插值方法,将样条曲线严格约束于给定的折线之上、之下或之间的问题都可以得到解决同时还研究了这种加权有理三次插值的逼近性质。     

一类带参数的有理三次三角Hermite插值样条

给出一种带有参数的有理三次三角Hermite插值样条,具有标准三次Hermite插值样条相似的性质.利用参数的不同取值不但可以调控插值曲线的形状,而且比标准三次Hermite插值样条更好地逼近被插曲线.此外,选择合适的控制点,该种插值样条可以精确表示星形线和四叶玫瑰线等超越曲线.     

一类四次有理插值样条的点控制

构造了一种有理四次插值样条,其分子为四次多项式分母为二次多项式.该有理插值样条是有界的、保单调且C~2连续的,仅带有一个调节参数δ_i.研究了有理四次插值样条的性质,同时给出了相应的函数值控制、导数值控制方法,这种方法的优点在于能够根据实际设计需要简单地选取适宜的参数,达到对曲线的形状进行局部调控的目的.     

局部形状可调整的三次有理B样条插值曲线

利用三次非均匀有理B样条,给出了一种构造局部插值曲线的方法,生成的插值曲线是C2连续的.曲线表示式中带有一个局部形状参数,随着一个局部形状参数值的增大,所给曲线将局部地接近插值点构成的控制多边形.基于三次非均匀有理B样条函数的局部单调性和一种保单调性的准则,给出了所给插值曲线的保单调性的条件.     

Ⅱ型三角剖分上一类C2-连续的三次样条插值与逼近

本文研究矩形区域在Ⅱ-型三角剖分下二元三次样条的C2-连续的插值问题.首先给出了一类具有C2-连续的二元三次样条插值格式,然后证明了分片样条的存在性与唯-性,并给出了它的表达式和逼近度.     

一类具有C^2-拼接的二元三次样条的插值分析

研究了矩形区域在Ⅱ型三角剖分下具有C2-拼接的二元三次样条插值与逼近问题.给出了一类具有C2-拼接的二元三次样条的插值条件,存在性,唯一性,逼近度估计及其凸性分析.     

一种保凸的Spline插值方法

本文构造笛氏坐标系中一条光滑曲线,使它通过两个有特定切向的给定点,给出了此种插值函数保凸的一个充要条件.文中考虑逐段三次多项式的保凸插值函数,其收敛性的阶与三次样条多项式一样.最后叙述插值函数形状控制的方法.     

几种有理插值函数的逼近性质

1　引　　言在曲线和曲面设计中,样条插值是有用的和强有力的工具.不少作者已经研究了很多种类型的样条插值[1,2,3,4].近些年来,有理插值样条,特别是三次有理插值样条,以及它们在外型控制中的应用,已有了不少工作[5,6,7].有理插值样条的表达式中有某些参数,正是由于这些参数,有理插值样条在外型控制中充分显示了它的灵活性;但也正是由于这些参数,使它的逼近性质的研究增加了困难.因此,关于有理插值样条的逼近性质的研究很少见诸文献.本文在第二节首先叙述几种典型的有理插值样条,其中包括分母为一次、二次的三次有理插值样条和仅基于函数值…     

Shape control of curve design by weighted rational spline

Controlling the convexity and the strain energy of the interpolating curve can be carried out by controlling the second-order derivative of the interpolating function. In [1], the rational cubic spline with linear denominator has been used to constrain the convexity and the strain energy of the interpolating curves, but it does not work in some case. This paper deals with the weighted rational cubic spline with linear denominator for this kind of constraint, the sufficient and necessary condition for controlling the convexity and strain energy of the interpolating curves are derived, and a numerical example is given.     

Some approximation properties of periodic parametric cubic splines

The parametric cubic splines interpolating to such closed curves as the circle and ellipse are derived in a form where their parameters are given by simple algebraic expressions. The structure of these expressions enables the error in approximation of the given curves to be precisely determined and some additional features of the spline deduced.     

一种保形C~1三次样条插值方法

本文得到了构造一个保形Ｃ１三次插值样条函数的充要条件，并给出了一种构造保形Ｃ１三次插值样条函数的方法．     

An interpolation method by bivariate cubic splines with <Emphasis Type="Italic">c</Emphasis><Superscript>2</Superscript>-join on type-II triangulars at a rectangular domain

In this paper, an interpolating method for bivariate cubic splines with C ²-join on type-II triangular at a rectangular domain is given, and the approximation degree, interpolating existence and uniqueness of the cubic splines are studied. Supported by NSFC General Projects(60473130).     

CONSTRAINED RATIONAL CUBIC SPLINE AND ITS APPLICATION

1. IntroductionDesign of high quality, manufacturable surfaces, such as the outer shape of a ship, car oraeroplane, is an important yet challenging task in today's manufacturing industries. Althoughsignificam progress has been made in the last decade in developing and commercializing pro--duction quality CAD tools, demand for more effective tools is still high due to the ever increajsein model complexity and the needs to address and incorporate manufacturing requirements inthe early stage of …     

AN INTERPOLATION METHOD BY BIVARIATE CUBIC SPLINES WITH C~2 -JOIN ON TYPE-II TRIANGULARS AT A RECTANGULAR DOMAIN

In this paper, an interpolating method for bivariate cubic splines with C2-join on type-II triangular at a rectangular domain is given, and the approximation degree, inter-polating existence and uniqueness of the cubic splines are studied.