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authordos-reis <gdr@axiomatics.org>2007-08-14 05:14:52 +0000
committerdos-reis <gdr@axiomatics.org>2007-08-14 05:14:52 +0000
commitab8cc85adde879fb963c94d15675783f2cf4b183 (patch)
treec202482327f474583b750b2c45dedfc4e4312b1d /src/input/images1a.input.pamphlet
downloadopen-axiom-ab8cc85adde879fb963c94d15675783f2cf4b183.tar.gz
Initial population.
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+\documentclass{article}
+\usepackage{axiom}
+\begin{document}
+\title{\$SPAD/src/input images1a.input}
+\author{The Axiom Team}
+\maketitle
+\begin{abstract}
+\end{abstract}
+\eject
+\tableofcontents
+\eject
+\section{License}
+<<license>>=
+--Copyright The Numerical Algorithms Group Limited 1994-1996.
+@
+<<*>>=
+<<license>>
+
+-- Create a (p,q) torus-knot with radius r around the curve.
+-- The formula was derived by Larry Lambe.
+
+-- To produce a trefoil knot:
+-- torusKnot(2, 3, 0.5, 10, 200)
+
+-- compile, don't interpret functions
+)set function compile on
+
+-- Generalized tubes.
+-- These functions draw a 2-d curve in the normal
+-- planes around a 3-d curve. The computations are all done
+-- numerically in machine-precision floating point for efficiency.
+
+R3 := Point DoubleFloat -- Points in 3-Space
+R2 := Point DoubleFloat -- Points in 2-Space
+S := Segment Float -- Draw ranges
+ThreeCurve := DoubleFloat -> R3 -- type of a space curve function
+TwoCurve := (DoubleFloat, DoubleFloat) -> R2 -- type of a plane curve function
+Surface := (DoubleFloat, DoubleFloat) -> R3 -- type of a parameterized surface function
+
+-- Frenet frames define a coordinate system around a point on a space curve
+FrenetFrame := Record(value: R3, tagent: R3, normal: R3, binormal: R3)
+
+-- Holds current Frenet frame for a point on a curve
+frame: FrenetFrame
+
+-- compile, don't interpret functions
+)set fun compile on
+
+-- Draw a generalized tube.
+-- ntubeDraw(spaceCurve, planeCurve, u0..u1, t0..t1)
+-- draws planeCurve int the normal planes of spaceCurve. u0..u1 specifies
+-- the paramter range of the planeCurve and t0..t1 specifies the parameter
+-- range of the spaceCurve. Additionally the plane curve function takes
+-- as a second parameter the current parameter of the spaceCurve. This
+-- allows the plane curve to evolve as it goes around the space curve.
+-- see "page5.input" for an example of this.
+ntubeDraw: (ThreeCurve, TwoCurve, S, S) -> VIEW3D
+ntubeDraw(spaceCurve, planeCurve, uRange, tRange) ==
+ ntubeDrawOpt(spaceCurve, planeCurve, uRange, tRange, []$List DROPT)
+
+-- ntuberDrawOpt is the same as ntuberDraw, but takes optional
+-- parameters which it passes to the draw command.
+ntubeDrawOpt: (ThreeCurve, TwoCurve, S, S, List DROPT) -> VIEW3D
+ntubeDrawOpt(spaceCurve, planeCurve, uRange, tRange, l) ==
+ delT:DoubleFloat := (hi(tRange) - lo(tRange))/10000
+ oldT:DoubleFloat := lo(tRange) - 1
+ fun := ngeneralTube(spaceCurve, planeCurve, delT, oldT)
+ draw(fun, uRange, tRange, l)
+
+-- nfrenetFrame(c, t, delT) numerically computes the Frenet Frame
+-- about the curve c at t. delT is a small number used to
+-- compute derivatives.
+nfrenetFrame(c, t, delT) ==
+ f0 := c(t)
+ f1 := c(t+delT)
+ t0 := f1 - f0 -- the tangent
+ n0 := f1 + f0
+ b := cross(t0, n0) -- the binormal
+ n := cross(b,t0) -- the normal
+ ln := length n
+ lb := length b
+ ln = 0 or lb = 0 => error "Frenet Frame not well defined"
+ n := (1/ln)*n -- make into unit length vectors
+ b := (1/lb)*b
+ [f0, t0, n, b]$FrenetFrame
+
+-- nGeneralTube(spaceCurve, planeCurve, delT, oltT)
+-- creates a function which can be passed to the system draw command.
+-- The function is a parameterized surface for the general tube
+-- around the spaceCurve. delT is a small number used to compute
+-- derivatives, and oldT is used to hold the current value of the
+-- t parameter for the spaceCurve. This is an efficiency measure
+-- to ensure that frames are only computed once for every value of t.
+ngeneralTube: (ThreeCurve, TwoCurve, DoubleFloat, DoubleFloat) -> Surface
+ngeneralTube(spaceCurve, planeCurve, delT, oldT) ==
+ free frame
+ (v:DoubleFloat, t: DoubleFloat): R3 +->
+ if (t ~= oldT) then
+ frame := nfrenetFrame(spaceCurve, t, delT)
+ oldT := t
+ p := planeCurve(v, t)
+ frame.value + p.1*frame.normal + p.2*frame.binormal
+
+-- Create a (p,q) torus-knot with radius r around the curve.
+-- The formula was derived by Larry Lambe.
+-- To produce a trefoil knot:
+-- torusKnot(2, 3, 0.5)
+torusKnot(p:DFLOAT, q:DFLOAT, r:DFLOAT, uSteps:PI, tSteps:PI):VIEW3D ==
+ -- equation for the torus knot
+ knot := (t:DFLOAT):Point DFLOAT +->
+ fac := 4/(2.2@DFLOAT-sin(q*t))
+ fac * point [cos(p*t), sin(p*t), cos(q*t)]
+ -- equation for the cross section of the tube
+ circle := (u:DFLOAT, t:DFLOAT):Point DFLOAT +->
+ r * point [cos u, sin u]
+ -- draw the tube around the knot
+ ntubeDrawOpt(knot, circle, 0..2*%pi, 0..2*%pi, var1Steps == uSteps,
+ var2Steps == tSteps)
+
+
+-- draw a (15,17) torus knot
+
+torusKnot(15,17, 0.1, 6, 700)
+@
+\eject
+\begin{thebibliography}{99}
+\bibitem{1} nothing
+\end{thebibliography}
+\end{document}