DOCSLIB.ORG

Three Improvements in Reduction and Computation of Elliptic Integrals

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Three Improvements in Reduction and Computation of Elliptic Integrals Volume 107, Number 5, September–October 2002 Journal of Research of the National Institute of Standards and Technology [J. Res. Natl. Inst. Stand. Technol. 107, 413–418 (2002)] Three Improvements in Reduction and Computation of Elliptic Integrals Volume 107 Number 5 September–October 2002 B. C. Carlson Three improvements in reduction and com- for the symmetric elliptic integral of the putation of elliptic integrals are made. 1. first kind. Its usefulness for elliptic inte- Ames Laboratory and Department Reduction formulas, used to express many grals, in particular, is important. of Mathematics, elliptic integrals in terms of a few stan- Iowa State University, dard integrals, are simplified by modifying Key words: computational algorithm; ele- the definition of intermediate “basic inte- Ames, IA 50011-3020 mentary symmetric function; elliptic inte- grals.” 2. A faster than quadratically con- gral; hyperelliptic integral; hypergeometric vergent series is given for numerical R-function; recurrence relations; series computation of the complete symmetric el- expansion. liptic integral of the third kind. 3. A se- ries expansion of an elliptic or hyperelliptic integral in elementary symmetric func- Accepted: August 6, 2002 tions is given, illustrated with numerical co- efficients for terms through degree seven Available online: http://www.nist.gov/jres Foreword Elliptic integrals have many applications, for example references to extensions and generalizations, graphs, in mathematics and physics: brief descriptions of computational methods, a survey of • arclengths of plane curves (ellipse, hyperbola, useful published tables, and sample applications. The Bernoulli’s lemniscate) Web site will include, in addition, interactive visualiza- • surface area of an ellipsoid in 3-dimensional space tions of 3-dimensional surfaces, a mathematics-aware • electric and magnetic fields associated with ellipsoids search engine, a downloading capability for equations, • periodicity of anharmonic oscillators live links to Web sites that provide mathematical soft- • mutual inductance of coaxial circles ware, and a limited facility for generating tables on • age of the universe in a Friedmann model demand. These applications are mentioned in the chapter on el- The DLMF is modeled after the Handbook of Mathe- liptic integrals, written by B. C. Carlson, that will ap- matical Functions, published in 1964 by the National pear in the NIST Digital Library of Mathematical Func- Bureau of Standards with M. Abramowitz and I. A. tions. Stegun as editors. This handbook has been enormously The DLMF is scheduled to begin service in 2003 successful: it has sold more than 500,000 copies, its from a NIST Web site. A hardcover book will be pub- sales remain high, and it is very frequently cited in lished also. These resources will provide a complete journal articles in physics and many other fields. But guide to the higher mathematical functions for use by new properties of the higher functions have been devel- experienced scientific professionals. The book will oped, and new functions have risen in importance in provide mathematical formulas, references to proofs, applications, since the publication of the Abramowitz 413 Volume 107, Number 5, September–October 2002 Journal of Research of the National Institute of Standards and Technology and Stegun handbook. More than half of the old hand- which follows is an example. It is a further development book was devoted to tables, now made obsolete by the of material that appears in Carlson’s DLMF chapter on revolutionary improvements since 1964 in computers elliptic integrals. and software. The need for a modern reference is being filled by more than 30 expert authors who are working Daniel W. Lozier under contract to NIST and supervised by four NIST NIST Mathematical and Computational Sciences editors. The writing is being edited carefully to assure Division consistent style and level of content. Elliptic integrals have long been associated with the name of Legendre. Legendre’s incomplete elliptic inte- 1. Simplified Formulas for Reducing grals are Elliptic Integrals ␾ d␪ A large class of elliptic integrals can be written in the F(␾, k)=͵ , 2 2 0 ͙1 Ϫ k sin ␪ form x h n Ϫ ␾ ͵ ͹ 1/2 ͹ mj I(m)= (ai + bi t) (aj + bj t) dt, (1.1) E(␾, k)=͵ ͙1 Ϫ k 2 sin2 ␪ d␪, y i=1 j=1 0 where m =(m1,...,mn )isann-tuple of integers (posi- and tive, negative or zero), x > y, h = 3 or 4, n Ն h, and the different linear factors are not proportional. The a’s and ␾ d␪ b’s may be complex (with the b’s not equal to zero), but ⌸(␾, ␣ 2, k)=͵ . 2 2 2 2 0 ͙1 Ϫ k sin ␪ (1 Ϫ ␣ sin ␪) the integral is assumed to be well defined, possibly as a Cauchy principal value. In particular the line segment The complete forms of these integrals are obtained by with endpoints ai + bi x and ai + bi y is assumed to lie in setting ␾ = ␲/2. the cut plane C\(( Ϫϱ, 0) for 1 Յ i Յ h. ͚n Over a period of more than 35 years, Carlson has We write m = j=1 mj ej , where ej is an n-tuple with 1 published a series of papers that provide valuable new in the jth position and 0’s elsewhere, and we define mathematical and computational foundations for the 0 = (0, ..., 0). Reference [1] gives a general method of subject in terms of the symmetric elliptic integrals reducing I(m) to a linear combination of “basic inte- grals,” defined as I(0), I(Ϫej ), 1 Յ j Յ n, and (if h =4) ϱ Յ Յ 1 ͵ dt I(ek ), 1 k 4. A simple example of such a reduction RF (x, y, z)= , 2 0 s(t) is bi I(ej Ϫ ei )=dji I(Ϫei )+bj I(0), ϱ 3 ͵ dt RD (x, y, z)= , ʦ 2 0 s(t)(t + z) i, j {1, ..., n}, (1.2) where dji = ajbi Ϫ aibj . This equation reduces all 36+72 ϱ 3 ͵ dt integrals in Ref. [2], Eqs. (3.142) and (3.168) and also RJ (x, y, z, p)= 2 2 0 s(t)(t + p) the 18 integrals in Ref. [2], Eq. (3.159) after taking x as a new variable of integration. The basic integrals are where expressed in terms of symmetric standard integrals RF , RD ,andRJ in Ref. [1], Sec. 4. s(t)=͙t + x ͙t + y ͙t + z. The general method first reduces I(m) by Ref. [1], Eq. (2.19) to integrals in which m has at most one The complete forms are obtained by setting x =0.In nonzero component and then uses two recurrence rela- comparison with Legendre’s integrals, Carlson’s inte- tions Ref. [1] Eqs. (3.5) and (3.11) for further reduction grals simplify the reduction of general elliptic integrals to basic integrals. For example, the simplest recurrence to standard forms and open the way to efficient compu- relation is Ref. [1], Eq. (3.11): tations by application of a duplication theorem. q q Ϫ One of the purposes of the DLMF project is to stim- q ͸ͩ ͪ r q r ʦ ގ bi I(qej )= bj dji I(rei ), q . (1.3) ulate research into the theory, computation and applica- r=0 r tion of the higher mathematical functions. The paper 414 Volume 107, Number 5, September–October 2002 Journal of Research of the National Institute of Standards and Technology n ␣ ␣ The b’s appear also in the other two formulas and there- ␩Ϯ1 (i)иии␩Ϯs (i) ⌬ ͹ mj ˆ ˆ ͸ 1 s i = rji , C0(i)=1, CϮs (i)= ␣ иии␣ , fore in all reduction formulas, sometimes in great profu- j=1 1! s ! sion if m is considerably more complicated than in Eq. ji Ϫ n (1.2). ␩ 1 ͸ Ϯp Ն Ϯp (i)= mj rij , p 1, (1.11) It has been found that the b’s disappear from all three p j=1 formulas, and therefore from all reduction formulas, if ji we define where upper (lower) signs go together and the first sum Iˆ(m)=I(m)/B, Aˆ (m)=A(m)/B, extends over all nonnegative integers ␣1,...,␣s such that ␣1 +2␣2 +...+s␣s = s. A recurrence relation for the n d a a coefficients is ͹ mj ij i Ϫ j B = bj , rij = = . (1.4) j=1 bibj bi bj s ˆ ͸ ␩ ˆ Ն sCϮs (i)= p Ϯp (i) CϮ(sϪp)(i), s 1. (1.12) Here A(m) is the algebraic function p=1 A(m)=fm(x) Ϫ fm(y), (1.5) 2. Algorithms for Complete Elliptic where fm(t) is the integrand of Eq. (1.1). Note that Integrals of the Third Kind Iˆ(0)=I(0). For example, Eq. (1.2) becomes Complications formerly encountered in numerical computation of Legendre’s complete elliptic integral of Iˆ(ej Ϫ ei )=rji Iˆ(Ϫei )+I(0), (1.6) the third kind were avoided by defining and tabulating Heuman’s Lambda function (for circular cases) and a and Eq. (1.3) becomes modification of Jacobi’s Zeta function (for hyperbolic cases). For example, the method of Ref. [3] was later q q Ϫ ˆ ͸ͩ ͪ q r ˆ ʦ ގ superseded by Bartky’s transformation and its applica- I(qej )= rji I(rei ), q . (1.7) r=0 r tion by Bulirsch [4] to his complete integral cel(kc , p, a, b). Bartky’s transformation for the com- The other recurrence relation, Ref. [1], Eq. (3.5), be- plete case of the symmetric integral of the third kind, comes obtained from Ref. [5], Eq. (4.14) with the help of h ␲ Ϫ ͸ ˆ Ϫ (3 /4)RL (y, z, p)=3RF (0, y, z) pRJ (0, y, z, p), (2q + r)EhϪr (r1j ,...,rhj )I((q 1+r)ej ) r=0 (␲/2)RK (y, z)=RF (0, y, z), (2.1) h ˆ ͩ ͸ ͪ ʦ ޚ Յ Յ =2A qej + ei , q ,1 j n (1.8) i=1 can be written as 2 2 2 2 2 2 where EhϪr is the elementary symmetric function de- RJ (0, gn , an , pn )=snRJ (0, gn+1, an+1, pn+1) fined by 2 2 2 + (3/2pn )RF (0, gn+1, an+1), (2.2) h h ͹ ͸ k (1 + trij )= t Ek (r1j ,...,rhj ), (1.9) 4 Ϫ 2 2 4 i=1 k=0 where an , gn , pn are positive, sn =(pn an gn )/8pn ,and 2 whence Eh = 0 if 1 Յ j Յ h because rjj =0.
Load more

Recommended publications
  • Nonintersecting Brownian Motions on the Unit Circle: Noncritical Cases
    The Annals of Probability 2016, Vol. 44, No. 2, 1134–1211 DOI: 10.1214/14-AOP998 c Institute of Mathematical Statistics, 2016 NONINTERSECTING BROWNIAN MOTIONS ON THE UNIT CIRCLE By Karl Liechty and Dong Wang1 DePaul University and National University of Singapore We consider an ensemble of n nonintersecting Brownian particles on the unit circle with diffusion parameter n−1/2, which are condi- tioned to begin at the same point and to return to that point after time T , but otherwise not to intersect. There is a critical value of T which separates the subcritical case, in which it is vanishingly un- likely that the particles wrap around the circle, and the supercritical case, in which particles may wrap around the circle. In this paper, we show that in the subcritical and critical cases the probability that the total winding number is zero is almost surely 1 as n , and →∞ in the supercritical case that the distribution of the total winding number converges to the discrete normal distribution. We also give a streamlined approach to identifying the Pearcey and tacnode pro- cesses in scaling limits. The formula of the tacnode correlation kernel is new and involves a solution to a Lax system for the Painlev´e II equation of size 2 2. The proofs are based on the determinantal × structure of the ensemble, asymptotic results for the related system of discrete Gaussian orthogonal polynomials, and a formulation of the correlation kernel in terms of a double contour integral. 1. Introduction. The probability models of nonintersecting Brownian motions have been studied extensively in last decade; see Tracy and Widom (2004, 2006), Adler and van Moerbeke (2005), Adler, Orantin and van Moer- beke (2010), Delvaux, Kuijlaars and Zhang (2011), Johansson (2013), Ferrari and Vet˝o(2012), Katori and Tanemura (2007) and Schehr et al.
    [Show full text]
  • Lecture 9 Riemann Surfaces, Elliptic Functions Laplace Equation
    Lecture 9 Riemann surfaces, elliptic functions Laplace equation Consider a Riemannian metric gµν in two dimensions. In two dimensions it is always possible to choose coordinates (x,y) to diagonalize it as ds2 = Ω(x,y)(dx2 + dy2). We can then combine them into a complex combination z = x+iy to write this as ds2 =Ωdzdz¯. It is actually a K¨ahler metric since the condition ∂[i,gj]k¯ = 0 is trivial if i, j = 1. Thus, an orientable Riemannian manifold in two dimensions is always K¨ahler. In the diagonalized form of the metric, the Laplace operator is of the form, −1 ∆=4Ω ∂z∂¯z¯. Thus, any solution to the Laplace equation ∆φ = 0 can be expressed as a sum of a holomorphic and an anti-holomorphid function. ∆φ = 0 φ = f(z)+ f¯(¯z). → In the following, we assume Ω = 1 so that the metric is ds2 = dzdz¯. It is not difficult to generalize our results for non-constant Ω. Now, we would like to prove the following formula, 1 ∂¯ = πδ(z), z − where δ(z) = δ(x)δ(y). Since 1/z is holomorphic except at z = 0, the left-hand side should vanish except at z = 0. On the other hand, by the Stokes theorem, the integral of the left-hand side on a disk of radius r gives, 1 i dz dxdy ∂¯ = = π. Zx2+y2≤r2 z 2 I|z|=r z − This proves the formula. Thus, the Green function G(z, w) obeying ∆zG(z, w) = 4πδ(z w), − should behave as G(z, w)= log z w 2 = log(z w) log(¯z w¯), − | − | − − − − near z = w.
    [Show full text]
  • Lectures on the Combinatorial Structure of the Moduli Spaces of Riemann Surfaces
    LECTURES ON THE COMBINATORIAL STRUCTURE OF THE MODULI SPACES OF RIEMANN SURFACES MOTOHICO MULASE Contents 1. Riemann Surfaces and Elliptic Functions 1 1.1. Basic Definitions 1 1.2. Elementary Examples 3 1.3. Weierstrass Elliptic Functions 10 1.4. Elliptic Functions and Elliptic Curves 13 1.5. Degeneration of the Weierstrass Elliptic Function 16 1.6. The Elliptic Modular Function 19 1.7. Compactification of the Moduli of Elliptic Curves 26 References 31 1. Riemann Surfaces and Elliptic Functions 1.1. Basic Definitions. Let us begin with defining Riemann surfaces and their moduli spaces. Definition 1.1 (Riemann surfaces). A Riemann surface is a paracompact Haus- S dorff topological space C with an open covering C = λ Uλ such that for each open set Uλ there is an open domain Vλ of the complex plane C and a homeomorphism (1.1) φλ : Vλ −→ Uλ −1 that satisfies that if Uλ ∩ Uµ 6= ∅, then the gluing map φµ ◦ φλ φ−1 (1.2) −1 φλ µ −1 Vλ ⊃ φλ (Uλ ∩ Uµ) −−−−→ Uλ ∩ Uµ −−−−→ φµ (Uλ ∩ Uµ) ⊂ Vµ is a biholomorphic function. Remark. (1) A topological space X is paracompact if for every open covering S S X = λ Uλ, there is a locally finite open cover X = i Vi such that Vi ⊂ Uλ for some λ. Locally finite means that for every x ∈ X, there are only finitely many Vi’s that contain x. X is said to be Hausdorff if for every pair of distinct points x, y of X, there are open neighborhoods Wx 3 x and Wy 3 y such that Wx ∩ Wy = ∅.
    [Show full text]
  • Elliptic Curve Cryptography and Digital Rights Management
    Lecture 14: Elliptic Curve Cryptography and Digital Rights Management Lecture Notes on “Computer and Network Security” by Avi Kak ([email protected]) March 9, 2021 5:19pm ©2021 Avinash Kak, Purdue University Goals: • Introduction to elliptic curves • A group structure imposed on the points on an elliptic curve • Geometric and algebraic interpretations of the group operator • Elliptic curves on prime finite fields • Perl and Python implementations for elliptic curves on prime finite fields • Elliptic curves on Galois fields • Elliptic curve cryptography (EC Diffie-Hellman, EC Digital Signature Algorithm) • Security of Elliptic Curve Cryptography • ECC for Digital Rights Management (DRM) CONTENTS Section Title Page 14.1 Why Elliptic Curve Cryptography 3 14.2 The Main Idea of ECC — In a Nutshell 9 14.3 What are Elliptic Curves? 13 14.4 A Group Operator Defined for Points on an Elliptic 18 Curve 14.5 The Characteristic of the Underlying Field and the 25 Singular Elliptic Curves 14.6 An Algebraic Expression for Adding Two Points on 29 an Elliptic Curve 14.7 An Algebraic Expression for Calculating 2P from 33 P 14.8 Elliptic Curves Over Zp for Prime p 36 14.8.1 Perl and Python Implementations of Elliptic 39 Curves Over Finite Fields 14.9 Elliptic Curves Over Galois Fields GF (2n) 52 14.10 Is b =0 a Sufficient Condition for the Elliptic 62 Curve6 y2 + xy = x3 + ax2 + b to Not be Singular 14.11 Elliptic Curves Cryptography — The Basic Idea 65 14.12 Elliptic Curve Diffie-Hellman Secret Key 67 Exchange 14.13 Elliptic Curve Digital Signature Algorithm (ECDSA) 71 14.14 Security of ECC 75 14.15 ECC for Digital Rights Management 77 14.16 Homework Problems 82 2 Computer and Network Security by Avi Kak Lecture 14 Back to TOC 14.1 WHY ELLIPTIC CURVE CRYPTOGRAPHY? • As you saw in Section 12.12 of Lecture 12, the computational overhead of the RSA-based approach to public-key cryptography increases with the size of the keys.
    [Show full text]
  • Applications of Elliptic Functions in Classical and Algebraic Geometry
    APPLICATIONS OF ELLIPTIC FUNCTIONS IN CLASSICAL AND ALGEBRAIC GEOMETRY Jamie Snape Collingwood College, University of Durham Dissertation submitted for the degree of Master of Mathematics at the University of Durham It strikes me that mathematical writing is similar to using a language. To be understood you have to follow some grammatical rules. However, in our case, nobody has taken the trouble of writing down the grammar; we get it as a baby does from parents, by imitation of others. Some mathe- maticians have a good ear; some not... That’s life. JEAN-PIERRE SERRE Jean-Pierre Serre (1926–). Quote taken from Serre (1991). i Contents I Background 1 1 Elliptic Functions 2 1.1 Motivation ............................... 2 1.2 Definition of an elliptic function ................... 2 1.3 Properties of an elliptic function ................... 3 2 Jacobi Elliptic Functions 6 2.1 Motivation ............................... 6 2.2 Definitions of the Jacobi elliptic functions .............. 7 2.3 Properties of the Jacobi elliptic functions ............... 8 2.4 The addition formulæ for the Jacobi elliptic functions . 10 2.5 The constants K and K 0 ........................ 11 2.6 Periodicity of the Jacobi elliptic functions . 11 2.7 Poles and zeroes of the Jacobi elliptic functions . 13 2.8 The theta functions .......................... 13 3 Weierstrass Elliptic Functions 16 3.1 Motivation ............................... 16 3.2 Definition of the Weierstrass elliptic function . 17 3.3 Periodicity and other properties of the Weierstrass elliptic function . 18 3.4 A differential equation satisfied by the Weierstrass elliptic function . 20 3.5 The addition formula for the Weierstrass elliptic function . 21 3.6 The constants e1, e2 and e3 .....................
    [Show full text]
  • An Eloquent Formula for the Perimeter of an Ellipse Semjon Adlaj
    An Eloquent Formula for the Perimeter of an Ellipse Semjon Adlaj he values of complete elliptic integrals Define the arithmetic-geometric mean (which we of the first and the second kind are shall abbreviate as AGM) of two positive numbers expressible via power series represen- x and y as the (common) limit of the (descending) tations of the hypergeometric function sequence xn n∞ 1 and the (ascending) sequence { } = 1 (with corresponding arguments). The yn n∞ 1 with x0 x, y0 y. { } = = = T The convergence of the two indicated sequences complete elliptic integral of the first kind is also known to be eloquently expressible via an is said to be quadratic [7, p. 588]. Indeed, one might arithmetic-geometric mean, whereas (before now) readily infer that (and more) by putting the complete elliptic integral of the second kind xn yn rn : − , n N, has been deprived such an expression (of supreme = xn yn ∈ + power and simplicity). With this paper, the quest and observing that for a concise formula giving rise to an exact it- 2 2 √xn √yn 1 rn 1 rn erative swiftly convergent method permitting the rn 1 − + − − + = √xn √yn = 1 rn 1 rn calculation of the perimeter of an ellipse is over! + + + − 2 2 2 1 1 rn r Instead of an Introduction − − n , r 4 A recent survey [16] of formulae (approximate and = n ≈ exact) for calculating the perimeter of an ellipse where the sign for approximate equality might ≈ is erroneously resuméd: be interpreted here as an asymptotic (as rn tends There is no simple exact formula: to zero) equality.
    [Show full text]
  • §2. Elliptic Curves: J-Invariant (Jan 31, Feb 4,7,9,11,14) After
    24 JENIA TEVELEV §2. Elliptic curves: j-invariant (Jan 31, Feb 4,7,9,11,14) After the projective line P1, the easiest algebraic curve to understand is an elliptic curve (Riemann surface of genus 1). Let M = isom. classes of elliptic curves . 1 { } We are going to assign to each elliptic curve a number, called its j-invariant and prove that 1 M1 = Aj . 1 1 So as a space M1 A is not very interesting. However, understanding A ! as a moduli space of elliptic curves leads to some breath-taking mathemat- ics. More generally, we introduce M = isom. classes of smooth projective curves of genus g g { } and M = isom. classes of curves C of genus g with points p , . , p C . g,n { 1 n ∈ } We will return to these moduli spaces later in the course. But first let us recall some basic facts about algebraic curves = compact Riemann surfaces. We refer to [G] and [Mi] for a rigorous and detailed exposition. §2.1. Algebraic functions, algebraic curves, and Riemann surfaces. The theory of algebraic curves has roots in analysis of Abelian integrals. An easiest example is the elliptic integral: in 1655 Wallis began to study the arc length of an ellipse (X/a)2 + (Y/b)2 = 1. The equation for the ellipse can be solved for Y : Y = (b/a) (a2 X2), − and this can easily be differentiated !to find bX Y ! = − . a√a2 X2 − 2 This is squared and put into the integral 1 + (Y !) dX for the arc length. Now the substitution x = X/a results in " ! 1 e2x2 s = a − dx, 1 x2 # $ − between the limits 0 and X/a, where e = 1 (b/a)2 is the eccentricity.
    [Show full text]
  • Elliptic Functions and Elliptic Curves: 1840-1870
    Elliptic functions and elliptic curves: 1840-1870 2017 Structure 1. Ten minutes context of mathematics in the 19th century 2. Brief reminder of results of the last lecture 3. Weierstrass on elliptic functions and elliptic curves. 4. Riemann on elliptic functions Guide: Stillwell, Mathematics and its History, third ed, Ch. 15-16. Map of Prussia 1867: the center of the world of mathematics The reform of the universities in Prussia after 1815 Inspired by Wilhelm von Humboldt (1767-1835) Education based on neo-humanistic ideals: academic freedom, pure research, Bildung, etc. Anti-French. Systematic policy for appointing researchers as university professors. Research often shared in lectures to advanced students (\seminarium") Students who finished at universities could get jobs at Gymnasia and continue with scientific research This system made Germany the center of the mathematical world until 1933. Personal memory (1983-1984) Otto Neugebauer (1899-1990), manager of the G¨ottingen Mathematical Institute in 1933, when the Nazis took over. Structure of this series of lectures 2 p 2 ellipse: Apollonius of Perga (y = px − d x , something misses = Greek: elleipei) elliptic integrals, arc-length of an ellipse; also arc length of lemniscate elliptic functions: inverses of such integrals elliptic curves: curves of genus 1 (what this means will become clear) Results from the previous lecture by Steven Wepster: Elliptic functions we start with lemniscate Arc length is elliptic integral Z x dt u(x) = p 4 0 1 − t Elliptic function x(u) = sl(u) periodic with period 2! length of lemniscate. (x2 + y 2)2 = x2 − y 2 \sin lemn" polar coordinates r 2 = cos2θ x Some more results from u(x) = R p dt , x(u) = sl(u) 0 1−t4 sl(u(x)) = x so sl0(u(x)) · u0(x) = 1 so p 0 1 4 p 4 sl (u) = u0(x) = 1 − x = 1 − sl(u) In modern terms, this provides a parametrisation 0 x = sl(u); y = sl (pu) for the curve y = 1 − x4, y 2 = (1 − x4).
    [Show full text]
  • Leon M. Hall Professor of Mathematics University of Missouri-Rolla
    Special Functions Leon M. Hall Professor of Mathematics University of Missouri-Rolla Copyright c 1995 by Leon M. Hall. All rights reserved. Chapter 3. Elliptic Integrals and Elliptic Functions 3.1. Motivational Examples Example 3.1.1 (The Pendulum). A simple, undamped pendulum of length L has motion governed by the differential equation ′′ g u + sin u =0, (3.1.1) L where u is the angle between the pendulum and a vertical line, g is the gravitational constant, and ′ is differentiation with respect to time. Consider the “energy” function (some of you may recognize this as a Lyapunov function): ′ 2 u ′ 2 ′ (u ) g (u ) g E(u,u )= + sin z dz = + (1 cos u) . 2 L 2 L − Z0 For u(0) and u′(0) sufficiently small (3.1.1) has a periodic solution. Suppose u(0) = A and u′(0) = 0. At this point the energy is g (1 cos A), and by conservation of energy, we have L − (u′)2 g g + (1 cos u)= (1 cos A) . 2 L − L − Simplifying, and noting that at first u is decreasing, we get du 2g = √cos u cos A. dt − r L − This DE is separable, and integrating from u =0 to u = A will give one-fourth of the period. Denoting the period by T , and realizing that the period depends on A, we get 2L A du T (A)=2 . (3.1.2) s g 0 √cos u cos A Z − If A = 0 or A = π there is no motion (do you see why this is so physically?), so assume 0 <A<π.
    [Show full text]
  • Elliptic Curves: Number Theory and Cryptography
    Elliptic Curves Number Theory and Cryptography Second Edition © 2008 by Taylor & Francis Group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© 2008 by Taylor & Francis Group, LLC Continued Titles #%%#&(1'('%*"* -+$.'#*-%/$(.) +/%(%5/%*) ('%*"*'(-!%+,#'+('*(%)/*-%''#*-%/$(. !)!-/%*) )0(!-/%*) ) !-$ "*%+#''*'"*#+,()"*(!*+ !.%#)$!*-4 '!-1%--4*" -+$'#*-%/$(.) +/%(%5/%*) % *'2+-%.'(*+"(,'(,,'+,(' ) **&*"++'%! -4+/*#-+$4 #"*(%%#''#!-%0(!-$!*-4 #"*(%%#'* !.$! 0% !/*!-!4"-*()%!)//** !-)%(!. #"*(%%#' 0) (!)/'0(!-$!*-42%/$++'%/%*).!*)
    [Show full text]
  • Precise and Fast Computation of a General Incomplete Elliptic Integral
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Journal of Computational and Applied Mathematics 235 (2011) 4140–4148 Contents lists available at ScienceDirect Journal of Computational and Applied Mathematics journal homepage: www.elsevier.com/locate/cam Precise and fast computation of a general incomplete elliptic integral of second kind by half and double argument transformations Toshio Fukushima National Astronomical Observatory of Japan, 2-21-1, Ohsawa, Mitaka, Tokyo 181-8588, Japan article info a b s t r a c t Article history: We developed a method to compute simultaneously two associate incomplete elliptic Received 17 December 2010 integrals of the second kind, B.'jm/ and D.'jm/, by the half argument formulas of Jacobian Received in revised form 27 February 2011 elliptic functions and the double argument transformations of the integrals. The relative errors of the new method are sufficiently small as 5–10 machine epsilons. Meanwhile, Keywords: the new method runs 3–6 times faster than that using Carlson's RD. As a result, it enables Incomplete elliptic integral a precise and fast computation of arbitrary linear combination of the incomplete elliptic Jacobian elliptic function integrals of the first and the second kind, F jm and E jm . Half argument transformation .' / .' / ' 2011 Elsevier B.V. All rights reserved. 1. Introduction 1.1. Incomplete elliptic integrals of first and second kind The incomplete elliptic integrals of the first and the second kind are defined as Z ' dθ Z ' p F.'jm/ ≡ ; E.'jm/ ≡ 1 − m sin2 θ dθ: (1) p 2 0 1 − m sin θ 0 Their textbooks are [1,2] and references are [3–7].
    [Show full text]
  • An Introduction to the Equatorial Orbitals of Toy Neutron Stars
    An Introduction to the Equatorial Orbitals of Toy Neutron Stars Aubrey Truman ∗ Department of Mathematics, Computational Foundry, Swansea University Bay Campus, Fabian Way, Swansea, SA1 8EN, UK September 16, 2019 Abstract In modelling the behaviour of ring systems for neutron stars in a non-relativistic setting one has to combine Newton’s inverse square law of force of gravity with the Lorentz force due to the magnetic dipole moment in what we refer to as the KLMN equation. Here we investigate this problem using analytical dynamics revealing a strong link between Weierstrass functions and equatorial orbitals. The asymptotics of our solutions reveal some new physics involving unstable circular orbits with possible long term effects - doubly asymp- totic spirals, the hyperbolic equivalent of Keplerian ellipses in this set- ting. The corresponding orbitals can only arise when the discriminant of a certain quartic, Q; ∆4 = 0. When this occurs simultaneously with g3, its quartic invariant, changing sign, the physics changes dramat- ically. Here we introduce dimensionless variables Z and W for this problem, ∆4(Z; W ) = 0, is then an algebraic plane curve of degree 6 whose singularities reveal such changes in the physics. The use of polar coordinates displays this singularity structure very clearly. Our first result shows that a time-change in the equations ofmo- tion leads to a complete solution of this problem in terms of Weier- strass functions. Since Weierstrass’s results underlie this entire work we present this result first. Legendre’s work leads to a complete solu- tion. Both results reinforce the physical importance of the condition, ∗Email: [email protected] 1 ∆4 = 0, our final flourish being provided by Jacobi with his theta function.
    [Show full text]