尖点

In this paper, the method, which is based on the theory of envelope and continuous map, is investigated.

文中用此方法分析了一些曲线的重要几何性质，即曲线段上含有尖点、重结点和拐点以及不含这些点的用控制顶点相对位置表示的充分必要条件。

When propagating light\|ray passes through two fixed points in the gradient index mediums and a cuspidal variable\|point （at this point the trace equation of propagating light\|ray is non\|differentiable） at the borderline of two different GRIN mediums, the mathematical relationship, which the trace equation of propagating light\|ray and borderline equation of two different GRIN mediums should satisfy, is derived by the Fermat's principle and calculus of variation.

当光线通过梯度折射率介质中两个固定点和两个GRIN介质界线上的可动尖点（光线轨迹方程的不可微点）时，由费马原理和变分法运算推得传输光线的轨迹方程与两种不同GRIN介质的界线方程应满足的微分关系式。

The amount of track points, including the double cusp points, which could be mostly realized by this kind of synthetic problems, was analyzed.

分析了包括双尖点在内，该类综合问题最多能实现的轨迹点数目。

In the last part of the paper, we construct a family of 2 parameter cubic algebraic curves interpolating two given endpoints and two given tangent lines and two given curvatures at these two endpoints with different initial cases in detail.

引 言三次参数曲线在计算机辅助几何设计与计算机图形学领域一直扮演着十分重要的角色，这主要是由于三次参数曲线是具有奇异性的次数最低的曲线，这些奇异性包括尖点、拐点和闭圈。

Introduced is a kind of space uniform rational spline curve, which possesses tension parameters and is based on hyperbolic spline functions.

引入了基于双曲样条函数的、具有张力参数的空间有理等距节点样条参数曲线，给出了这种曲线在每个样条子区间上为挠曲线段的充分必要条件；分析了这种挠曲线段没有尖点、重结点和泛拐点的特性；因而在用于空间曲线几何造型时可避免奇异性。

The proposed method can reconstruct curves from data set with arbitrary topology, such as simply connected, multiple connected and closed scattered points, keep the shape characteristic of point set well, especially in the segments with high curvature, and provide effective methods and technologies for the screw reconstrucion.

因此最短路逼近算法有效地解决了单连通、多连通和封闭的数据点集的曲线重建问题，较好地保持了数据点集的形状和走向，尤其是带尖点的数据点集的形状特征，为旋转面、螺旋面和可展曲面面的重建提供了有效方法和技术。

Hence the study of geometric properties, which include the distribution of singular and inflection points and the convexity of parametric curves, is the key for designer to control the curves shape.

在计算机辅助几何设计的光顺曲线造型中，不希望曲线带有二重结点、尖点及多余拐点，因此对参数曲线的几何性质(包括奇、拐点分布及凸性等)的研究是控制其曲线形状的关键。

A cusp is also called a stationary point or point of retrogression gression.

尖点也叫做平稳点或逆行点。

This paper discusses singularities, inflection points and convexity of FB-spline curves in terms of their control polygons, and gives the necessary and sufficient conditions for testing when FB-spline curves have one or two inflection points, or a cusp, or a loop, or none of the above points by the envelope theory and the topological mapping method.

文章利用包络理论和拓扑映射的方法，讨论了FB-样条曲线的奇拐点和曲线性质，并给出了依据控制多边形判断FB-样条曲线出现1个或2个拐点、1个尖点、1个二重点以及处处为凸的充分必要条件；最后给出了FB-样条曲线的奇点、拐点以及二重点在λ-μ平面上的分布图。

A point at which a curve crosses itself and at which the two tangents to the curve coincide.

尖点，会切点曲线上的一个点，曲线在该点与其本身相交，曲线的两条切线在该点重合

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。