Abstract
In this chapter we shall develop the formalism of the calculus of variations in simple situations. After a brief review of the necessary and sufficient conditions for extrema of ordinary functions on ℝn, we investigate in Section 2 some of the basic necessary conditions that are to be satisfied by minimizers of variational integrals
.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
The reader may wonder why we operate with (math) instead of (math). Here we follow the custom of the theory of distributions. It has the advantage that one need not distinguish between “test functions” for differential equations of different orders. Note that, under our assumptions, (7) implies that δℱ(u,φ) holds for all (math).
For the computation of the surface area of the unit sphere in ℝn in terms of Euler’s Γ-function, (math), compare e.g. Courant-John [1] or Fleming [1].
This limit case is related to Sobolev’s inequality and to the isoperimetric inequality.
For the definition of the mean curvature, see the Supplement.
The assumption k(x) = k(-x) guaranteeing property (iv) of Lemma 1 below is often omitted.
This means that, locally, the graphs representing ∂Ω k converge in C 1 to the graphs of ∂Ω.
(E735) De insigni paradoxo quod in analysi maximorum et minimorum occurit, Mem. Acad. Sci. St. Pétersbourg 3 (1811), and Euler [1] Ser. I, vol. 25, 286–292. The paper was written in 1779. Here and in the future, the letter E, as in (E735), refers to Eneström’s catalogue of Euler’s papers; see: Jahresberichte der DMV, Ergänzungsband IV, 1910–1913.
For instance, if we choose α = β and i - k, (10) implies that F is a linear function of p i α . From here we may proceed by induction.
See Supplement, nr. 6.
Cf. for example H.M. Edwards, An appreciation of Kronecker, The Mathematical Intelligencer 9, Nr. 1,28–35(1987).
The calculus of variations is for functionals what the differential calculus is for functions.19
Memoire sur la manière de distinguer les maxima des minima dans le Calcul des Variations, Mémoires de l’Acad. roy. des Sciences (1786), 1788,7–37.
“That is the equation that Euler was the first to discover.”
Lagrange, Oeuvres [12], Vol. 14, pp. 138–144.
(E296) Elementa calculi variationum, Novi comment, acad. sei. Petrop. 10 (1764), 1766, 51–93; (E297) Analytica explicatio methodi maximorum et minimorum, Novi comment, acad. sci. Petrop. 10 (1764), 1766,94–134. Cf. also: Opera omnia, Ser. I, Vol. 25.
Essai d’une nouvelle méthode pour déterminer les maxima et les minima des formules intégrales indéfinies, Miscellanea Taurinensia 2 (1760/61), 1762,173–195; Sur la méthode des variations, Misc. Taur. 4 (1766/69), 1771, 163–187.
(E385) Institutionum calculi integralis, Vol. 2, appendix: De calculo variationum, Petersburg 1770; cf. Euler [5].
(E420) Methodus nova et facilis calculum variationis tractandi, Novi Comment. Petropolis 16 (1771), 35–70.
Par. sav. étr. 7 (1773), cf. Oeuvres 6, p. 349.
Par. Hist. 1787 (1789), p. 252; cf. Oeuvres 11, p. 278. In Par. Hist. 1782 (1785), p. 135 (Oeuvres 10, p. 302), Laplace had already given the formula with respect to polar coordinates.
According to H. Burkhardt and W.F. Meyer, Potentialtheorie, Enzyklopädie der Mathemat. Wissenschaften IIA7b, p. 468. See also: R. Murphy, Elementary principles of the theory of electricity, heat and molecular actions, 1, Cambridge 1823, p. 93.
N. Bull, philom. 3 (1813), p. 388.
Allgemeine Lehrsätze in Beziehung auf die im verkehrten Verhältnisse des Quadrats der Entfernung wirkenden Anziehungs- und Abstoßungskräfte, Result, aus d. Beob. des magn. Vereins im Jahre 1839, Leipzig 1840 (cf. Werke [1], Vol. 5, pp. 206–211).
(E258) Principia motus fluidorum, Novi comm. acad. sci. Petrop. 6 (1756/57), 1761, 271–311. (Cf. also: Opera omnia, Ser. II, Vol. 12,133–168.) According to Jacobi, a paper with the title “De motu fluidorum in genere” has been read to the Berlin Academy on August 31,1752.
Mémoires de l’Académie de Berlin (1747), p. 214.
Ueber die Darstellbarkeit einer Funktion durch eine trigonometrische Reihe, Habilitationsschrift, Göttingen 1854 (Göttinger Abh. 13 (1867)); cf. also Riemann’s Werke, second ed., XII, 227–271.
The rational mechanics of flexible or elastic bodies 1638–1788, in: Euler’s Opera omnia, Ser. II, Vol. XI2.
Mémoire sur la courbure des surfaces, Paris, Mémoires de Mathématique et de Physique (de savans étrangers) de l’Académie 10 (1785), 447–550 (lu 1776).
Methodus inveniendi lineas curvas [2], Chapter 5, nrs. 44 and 47 (pp. 194–198); cf. also Opera omnia, Ser. I, Vol. 24, pp. 182 and 185 (E65).
Principia generalia theoriae figurae fluidorum in statu aequilibrii, communicated to the Göttinger Ges. der Wiss. Sept. 28, 1829; appeared 1830, and also in Göttinger Abh. 7, 39–88 (1832); cf. Werke 5, 29–77.
Mémoire sur le calcul des variations, Mém. Acad. roy. Sci. 12,223–331 (1833), communicated Nov. 10,1831.
See Bolza [1], pp. 42–44, and Todhunter [1], p. 54, nr. 84, remark (3).
Jacobi’s Variations-Rechnung, handwritten notes of lectures held by Jacobi (1837/38). The notes were taken by Rosenhain. The original text is the following: Es haben sich in der neuesten Zeit die ausgezeichnetsten Mathematiker me Poisson und Gauss mit der Auffindung der Variation des Doppelintegrals beschäftigt, die wegen der willkürlichen Funktionen unendliche Schwierigkeiten macht. Dennoch wird man durch ganz gewöhnliche Aufgaben darauf geführt, z.B. durch das Problem: unter allen Oberflächen, die durch ein schiefes Viereck im Raum gelegt werden können, diejenige anzugeben, welche den kleinsten Flächeninhalt hat. Es ist mir nicht bekannt, daß schon irgend jemand daran gedacht hätte, die zweite Variation solcher Doppelintegrale zu untersuchen-, auch habe ich, trotz vieler Mühe, nur erkannt, daß der Gegenstand zu den allerschwierig-sten gehört.”
Methodus inveniendi (E65), Chapter 1, nr. 34, and Chapter 2, nr. 50.
Author information
Authors and Affiliations
Rights and permissions
Copyright information
© 2004 Springer-Verlag Berlin Heidelberg
About this chapter
Cite this chapter
Giaquinta, M., Hildebrandt, S. (2004). The First Variation. In: Calculus of Variations I. Grundlehren der mathematischen Wissenschaften, vol 310. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-662-03278-7_1
Download citation
DOI: https://doi.org/10.1007/978-3-662-03278-7_1
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-642-08074-6
Online ISBN: 978-3-662-03278-7
eBook Packages: Springer Book Archive