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Bohumír Bastl The second reason for writing such a package followed from solving the project “Realization of interactively-information portal for scientific technical applications” which Department of Mathematics on our faculty obtained from Ministry of Education, Youth and Sports in 2004. The aim of this project is to create a new web portal, at this time located on http://webmath.zcu.cz, based on webMathematica software, which will provide different kinds of scientific computations. The computation and visualization of CAGD objects is also integrated to this web portal and anyone can use it. 2 Description of the package After loading the package to Mathematica kernel by standard Mathematica command Clamped,{{-10,-10},{-10,0}}] the figure (see Fig. 1 (right)) and the parametrization of the cubic spline for given points and boundary conditions (tangent vectors in the first and last points, here) are obtained. 50

CAGD PACKAGE FOR MATHEMATICA 10 7.5 5 2.5 6 4 2 -1 1 2 3 4 5 6 -2.5 -5 -7.5 -1 1 2 3 4 5 -2 -4 Figure 1: Quadratic and cubic splines. 10 2 6.1 9.1 1.1 4.1 0.1 7.1 8.1 3.1 5.1 2.1 8 6 4 2 4 6 8 10 1 Figure 2: Bézier and rational Bézier curves. Bézier objects belong to basic and very important CAGD objects. For given control polygon of n + 1 control points P i ,i = 0,...,n, or control net of (n + 1)(m + 1) control points P ij ,i = 0,...,n,j = 0,...,m respectively, the Bézier curve, or the Bézier surface respectively, is defined in the following way P(t) = n∑ P i Bi n (t), P(u,v) = i=0 n∑ i=0 j=0 m∑ P ij Bi n (u)Bj m (v) (1) where Bi n (t) are Bernstein polynomials of nth degree. The package provides functions Bernstein[] for computation of Bernstein polynomials, BezierCurve[] and BezierSurface[] for obtaining parametrizations andPlotBezierCurve[] andPlotBezierSurface[] for visualization of Bézier objects (see Fig. 2 (left) and 3 (left)). Rational Bézier objects are important for representation of curves or surfaces which cannot be parametrized by polynomial parametrizations, only by rational, e.g. arc of a circle. To each control point P i 51

Bohumír Bastl<br />

The second reason for writing such a package followed from solving<br />

the project “Realization of interactively-information portal for scientific<br />

technical applications” which Department of Mathematics on<br />

our faculty obtained from Ministry of Education, Youth and Sports<br />

in 2004. The aim of this project is to create a new web portal, at<br />

this time located on http://webmath.zcu.cz, based on webMathematica<br />

software, which will provide different kinds of scientific computations.<br />

The computation and visualization of CAGD objects is also<br />

integrated to this web portal and anyone can use it.<br />

2 Description of the package<br />

After loading the package to Mathematica kernel by standard Mathematica<br />

command Clamped,{{-10,-10},{-10,0}}]<br />

the figure (see Fig. 1 (right)) and the parametrization of the cubic<br />

spline for given points and boundary conditions (tangent vectors in<br />

the first and last points, here) are obtained.<br />

50

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