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Wirtinger's inequality for functions

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The three versions of the Wirtinger inequality can all be proved by various means. This is illustrated in the following by a different kind of proof for each of the three Wirtinger inequalities given above. In each case, by a linear
3853: 4145: 786: 3946: 2150: 4797: 2622: 2844: 108: 3961: 545: 339: 4420: 1329: 2074:{\displaystyle |y(x)|=\left|\int _{0}^{x}y'(x)\,\mathrm {d} x\right|\leq \int _{0}^{x}|y'(x)|\,\mathrm {d} x\leq {\sqrt {x}}\left(\int _{0}^{x}y'(x)^{2}\,\mathrm {d} x\right)^{1/2},} 3260:{\displaystyle y(x)-y_{n}(x)=\int _{0}^{x}{\big (}y_{n}'(z)-g_{n}(z){\big )}\,\mathrm {d} z-\int _{0}^{1}\int _{0}^{w}(y_{n}'(z)-g_{n}(z){\big )}\,\mathrm {d} z\,\mathrm {d} w} 1095: 3642:
The second and third versions of the Wirtinger inequality can be extended to statements about first Dirichlet and Neumann eigenvalues of the Laplace−Beltrami operator on
963: 3552:
These can also be extended to statements about higher-dimensional spaces. For example, the Riemannian circle may be viewed as the one-dimensional version of either a
2560:{\displaystyle \int _{0}^{1}Tf(x)^{2}\,\mathrm {d} x\leq \pi ^{-2}\int _{0}^{1}f(x)Tf(x)\,\mathrm {d} x={\frac {1}{\pi ^{2}}}\int _{0}^{1}(Tf)'(x)^{2}\,\mathrm {d} x} 1744:
This proves the Wirtinger inequality, since the second integral is clearly nonnegative. Furthermore, equality in the Wirtinger inequality is seen to be equivalent to
4425:
which is the isoperimetric inequality. Furthermore, equality in the isoperimetric inequality implies both equality in the Wirtinger inequality and also the equality
1734:{\displaystyle \int _{0}^{\pi }y(x)^{2}\,\mathrm {d} x+\int _{0}^{\pi }{\big (}y'(x)-y(x)\cot x{\big )}^{2}\,\mathrm {d} x=\int _{0}^{\pi }y'(x)^{2}\,\mathrm {d} x.} 54:
for curves in the plane. A variety of closely related results are today known as Wirtinger's inequality, all of which can be viewed as certain forms of the
22: 3759: 4325:{\displaystyle \int _{0}^{2\pi }{\big (}x'(t)+y(t){\big )}^{2}\,\mathrm {d} t+\int _{0}^{2\pi }{\big (}y'(t)^{2}-y(t)^{2}{\big )}\,\mathrm {d} t.} 929:{\displaystyle y(x)={\frac {1}{2}}a_{0}+\sum _{n\geq 1}\left(a_{n}{\frac {\sin nx}{\sqrt {\pi }}}+b_{n}{\frac {\cos nx}{\sqrt {\pi }}}\right),} 4675: 1236:
and since the summands are all nonnegative, the Wirtinger inequality is proved. Furthermore it is seen that equality holds if and only if
4371:
have average value zero. Then the Wirtinger inequality can be applied to see that the second integral is also nonnegative, and therefore
4722: 4659: 3872: 1293: 2767:{\displaystyle y_{n}(x)=\int _{0}^{x}g_{n}(z)\,\mathrm {d} z-\int _{0}^{1}\int _{0}^{w}g_{n}(z)\,\mathrm {d} z\,\mathrm {d} w.} 1521: 2090: 727:
Despite their differences, these are closely related to one another, as can be seen from the account given below in terms of
3379: 2977:{\displaystyle \int _{0}^{1}y_{n}(x)^{2}\,\mathrm {d} x\leq {\frac {1}{\pi ^{2}}}\int _{0}^{1}y_{n}'(x)^{2}\,\mathrm {d} x.} 4873: 241:{\displaystyle \int _{0}^{L}y(x)^{2}\,\mathrm {d} x\leq {\frac {L^{2}}{4\pi ^{2}}}\int _{0}^{L}y'(x)^{2}\,\mathrm {d} x,} 4129:{\displaystyle {\frac {L^{2}}{2\pi }}-2A=\int _{0}^{2\pi }{\big (}x'(t)^{2}+y'(t)^{2}+2y(t)x'(t){\big )}\,\mathrm {d} t} 3326: 2326: 673:{\displaystyle \int _{0}^{L}y(x)^{2}\,\mathrm {d} x\leq {\frac {L^{2}}{\pi ^{2}}}\int _{0}^{L}y'(x)^{2}\,\mathrm {d} x.} 467:{\displaystyle \int _{0}^{L}y(x)^{2}\,\mathrm {d} x\leq {\frac {L^{2}}{\pi ^{2}}}\int _{0}^{L}y'(x)^{2}\,\mathrm {d} x,} 3293: 1510:{\displaystyle y(x)^{2}+{\big (}y'(x)-y(x)\cot x{\big )}^{2}=y'(x)^{2}-{\frac {d}{dx}}{\big (}y(x)^{2}\cot x{\big )}.} 753: 4830: 4764: 4377: 1795:
There is a subtlety in the above application of the fundamental theorem of calculus, since it is not the case that
756:
in the integrals involved, there is no loss of generality in only proving the theorem for one particular choice of
4863: 777: 3710: 51: 3564:(of arbitrary dimension). The Wirtinger inequality, in the first version given here, can then be seen as the 4752: 1767: 3285: 954: 732: 55: 1226:{\displaystyle \int _{0}^{2\pi }y'(x)^{2}\,\mathrm {d} x=\sum _{n=1}^{\infty }n^{2}(a_{n}^{2}+b_{n}^{2})} 4868: 3609:, and the corresponding eigenfunctions are the restrictions of the homogeneous quadratic polynomials on 3557: 2354: 740: 35: 2575: 1835: 3370:, the three versions of the Wirtinger inequality above can be rephrased as theorems about the first 3284:
is a function for which equality in the Wirtinger inequality holds, then a standard argument in the
3420:, and the corresponding eigenfunctions are the linear combinations of the two coordinate functions. 3383: 1079:{\displaystyle \int _{0}^{2\pi }y(x)^{2}\,\mathrm {d} x=\sum _{n=1}^{\infty }(a_{n}^{2}+b_{n}^{2})} 4718: 4671: 3391: 3367: 728: 43: 4335:
The first integral is clearly nonnegative. Without changing the area or length of the curve,
3354:
To make this argument fully formal and precise, it is necessary to be more careful about the
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be a differentiable embedding of the circle in the plane. Parametrizing the circle by
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the first Dirichlet eigenvalue of the Laplace−Beltrami operator on the unit ball in
3598: 3679:
the first Neumann eigenvalue of the Laplace−Beltrami operator on the unit ball in
3709:
In the first form given above, the Wirtinger inequality can be used to prove the
3325:, and the regularity theory of such equations, followed by the usual analysis of 4822: 4818: 4748: 4651: 3643: 3423:
the first Dirichlet eigenvalue of the Laplace–Beltrami operator on the interval
31: 4667: 3487:
the first Neumann eigenvalue of the Laplace–Beltrami operator on the interval
3371: 2599:
be a sequence of compactly supported continuously differentiable functions on
4541: 4539: 4537: 3848:{\displaystyle \int _{0}^{2\pi }{\sqrt {x'(t)^{2}+y'(t)^{2}}}\,\mathrm {d} t} 3002:, and thereby prove the Wirtinger inequality, as soon as it is verified that 3634:, and the corresponding eigenfunctions are arbitrary linear combinations of 3685:
is the square of the smallest positive zero of the first derivative of the
42:
is an important inequality for functions of a single variable, named after
3583:, and the corresponding eigenfunctions are the linear combinations of the 3575:
the first eigenvalue of the Laplace–Beltrami operator on the unit-radius
731:. They can also all be regarded as special cases of various forms of the 739:
identified explicitly. The middle version is also a special case of the
4656:
Functional analysis, Sobolev spaces and partial differential equations
3553: 66:
There are several inequivalent versions of the Wirtinger inequality:
4556: 4554: 3597:-dimensional real projective space (with normalization given by the 4619: 4617: 3561: 2822:
has average value zero. So application of the above inequality to
2238:
converges to zero. In exactly the same way, it can be proved that
4829:. Princeton Mathematical Series. Vol. 32. Princeton, NJ: 3618:
the first eigenvalue of the Laplace–Beltrami operator on the
3593:
the first eigenvalue of the Laplace–Beltrami operator on the
3390:
the first eigenvalue of the Laplace–Beltrami operator on the
4705:. Pure and Applied Mathematics. Vol. 115. Orlando, FL: 526:
be a continuous and differentiable function on the interval
305:
be a continuous and differentiable function on the interval
74:
be a continuous and differentiable function on the interval
3941:{\displaystyle -\int _{0}^{2\pi }y(t)x'(t)\,\mathrm {d} t.} 3615:
to the unit sphere (and then to the real projective space).
1304:
Consider the second Wirtinger inequality given above. Take
1292:. This is equivalent to the stated condition by use of the 3327:
ordinary differential equations with constant coefficients
2327:
ordinary differential equations with constant coefficients
2268:
Consider the third Wirtinger inequality given above. Take
768:
Consider the first Wirtinger inequality given above. Take
2578:. Finally, for any continuously differentiable function 2145:{\displaystyle \int _{0}^{\pi }y'(x)^{2}\,\mathrm {d} x} 3273:
This proves the Wirtinger inequality. In the case that
4798:
Comptes Rendus des Séances de l'Académie des Sciences
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Introduction to Fourier analysis on Euclidean spaces
4635: 4545: 3638:-fold products of the eigenfunctions on the circles. 2574:
of average value zero, where the equality is due to
3660:is the square of the smallest positive zero of the 1834:. This is resolved as follows. It follows from the 4414: 4324: 4128: 3940: 3847: 3517:and the corresponding eigenfunctions are given by 3453:and the corresponding eigenfunctions are given by 3259: 2976: 2766: 2559: 2144: 2073: 1733: 1509: 1225: 1078: 928: 672: 466: 240: 21:For other inequalities named after Wirtinger, see 3023:. This is verified in a standard way, by writing 3270:and applying the Hölder or Jensen inequalities. 1766:, the general solution of which (as computed by 743:, again with the optimal constant identified. 4415:{\displaystyle {\frac {L^{2}}{4\pi }}\geq A,} 4305: 4252: 4209: 4169: 4112: 4019: 3951:Since the integrand of the integral defining 3234: 3138: 3087: 1657: 1608: 1499: 1464: 1406: 1357: 8: 4763:(Second edition of 1934 original ed.). 3705:Application to the isoperimetric inequality 4584: 4512:. These equations mean that the image of 4387: 4381: 4379: 4311: 4310: 4304: 4303: 4297: 4275: 4251: 4250: 4241: 4236: 4221: 4220: 4214: 4208: 4207: 4168: 4167: 4158: 4153: 4147: 4118: 4117: 4111: 4110: 4069: 4042: 4018: 4017: 4008: 4003: 3971: 3965: 3963: 3927: 3926: 3888: 3883: 3874: 3837: 3836: 3828: 3801: 3781: 3772: 3767: 3761: 3249: 3248: 3240: 3239: 3233: 3232: 3217: 3192: 3179: 3174: 3164: 3159: 3144: 3143: 3137: 3136: 3121: 3096: 3086: 3085: 3079: 3074: 3052: 3031: 2963: 2962: 2956: 2937: 2927: 2922: 2910: 2901: 2890: 2889: 2883: 2867: 2857: 2852: 2846: 2753: 2752: 2744: 2743: 2728: 2718: 2713: 2703: 2698: 2683: 2682: 2667: 2657: 2652: 2630: 2624: 2549: 2548: 2542: 2509: 2504: 2492: 2483: 2472: 2471: 2438: 2433: 2420: 2405: 2404: 2398: 2376: 2371: 2365: 2303:which is of average value zero, and with 2134: 2133: 2127: 2103: 2098: 2092: 2058: 2054: 2041: 2040: 2034: 2010: 2005: 1988: 1977: 1976: 1971: 1949: 1943: 1938: 1918: 1917: 1894: 1889: 1872: 1855: 1853: 1720: 1719: 1713: 1689: 1684: 1669: 1668: 1662: 1656: 1655: 1607: 1606: 1600: 1595: 1580: 1579: 1573: 1554: 1549: 1543: 1498: 1497: 1482: 1463: 1462: 1447: 1438: 1411: 1405: 1404: 1356: 1355: 1346: 1331: 1214: 1209: 1196: 1191: 1178: 1168: 1157: 1142: 1141: 1135: 1108: 1103: 1097: 1067: 1062: 1049: 1044: 1031: 1020: 1005: 1004: 998: 976: 971: 965: 895: 889: 859: 853: 832: 819: 805: 788: 659: 658: 652: 628: 623: 611: 601: 595: 584: 583: 577: 558: 553: 547: 453: 452: 446: 422: 417: 405: 395: 389: 378: 377: 371: 352: 347: 341: 227: 226: 220: 196: 191: 178: 164: 158: 147: 146: 140: 121: 116: 110: 4639: 4533: 3862:enclosed by the curve is given (due to 939:and the fact that the average value of 4623: 4608: 4596: 4572: 4560: 3626:-fold product of the circle of length 3713:for curves in the plane, as found by 7: 4793:"Sur le problème des isopérimètres" 50:in 1901 to give a new proof of the 4703:Eigenvalues in Riemannian geometry 4636:Hardy, Littlewood & Pólya 1952 4546:Hardy, Littlewood & Pólya 1952 4312: 4222: 4119: 3928: 3838: 3250: 3241: 3145: 2964: 2891: 2754: 2745: 2684: 2550: 2473: 2406: 2135: 2042: 1978: 1919: 1721: 1670: 1581: 1169: 1143: 1032: 1006: 684:and equality holds if and only if 660: 585: 478:and equality holds if and only if 454: 379: 252:and equality holds if and only if 228: 148: 14: 3687:Bessel function of the first kind 3662:Bessel function of the first kind 3622:-dimensional torus (given as the 2187:converges to zero is zero. Since 84:with average value zero and with 4524:is a round circle in the plane. 3601:from the unit-radius sphere) is 3747:has constant speed, the length 3292:must be a weak solution of the 2345:, the largest of which is then 1522:fundamental theorem of calculus 1294:trigonometric addition formulas 4294: 4287: 4272: 4265: 4203: 4197: 4188: 4182: 4107: 4101: 4090: 4084: 4066: 4059: 4039: 4032: 3955:is assumed constant, there is 3923: 3917: 3906: 3900: 3825: 3818: 3798: 3791: 3571:case of any of the following: 3544:for arbitrary nonzero numbers 3480:for arbitrary nonzero numbers 3229: 3223: 3207: 3201: 3185: 3133: 3127: 3111: 3105: 3064: 3058: 3042: 3036: 2953: 2946: 2880: 2873: 2740: 2734: 2679: 2673: 2642: 2636: 2539: 2532: 2525: 2515: 2468: 2462: 2453: 2447: 2395: 2388: 2276:. Given a continuous function 2124: 2117: 2031: 2024: 1972: 1968: 1962: 1950: 1914: 1908: 1873: 1869: 1863: 1856: 1710: 1703: 1642: 1636: 1627: 1621: 1570: 1563: 1479: 1472: 1435: 1428: 1391: 1385: 1376: 1370: 1343: 1336: 1312:. Any differentiable function 1220: 1184: 1132: 1125: 1073: 1037: 995: 988: 799: 793: 649: 642: 574: 567: 443: 436: 368: 361: 217: 210: 137: 130: 1: 4715:10.1016/s0079-8169(08)x6051-9 2838:is legitimate and shows that 2809:, which in turn implies that 2212:for small positive values of 536:with average value zero. Then 4563:, pp. 511–513, 576–578. 2788:has average value zero with 2084:which shows that as long as 1524:and the boundary conditions 3382:on various one-dimensional 2588:of average value zero, let 2286:of average value zero, let 4890: 4831:Princeton University Press 4765:Cambridge University Press 4658:. Universitext. New York: 4139:which can be rewritten as 2987:It is possible to replace 4668:10.1007/978-0-387-70914-7 3753:of the curve is given by 3380:Laplace–Beltrami operator 2325:. From basic analysis of 3711:isoperimetric inequality 2155:is finite, the limit of 1809:extends continuously to 1788:for an arbitrary number 52:isoperimetric inequality 4575:, Sections I.3 and I.5. 3579:-dimensional sphere is 3294:Euler–Lagrange equation 1768:separation of variables 1323:satisfies the identity 1260:, which is to say that 4701:Chavel, Isaac (1984). 4585:Stein & Weiss 1971 4494:for arbitrary numbers 4416: 4326: 4130: 3942: 3849: 3286:calculus of variations 3261: 2978: 2768: 2561: 2216:, it follows from the 2146: 2075: 1735: 1520:Integration using the 1511: 1227: 1173: 1080: 1036: 930: 780:are met, we can write 778:Dirichlet's conditions 674: 468: 242: 23:Wirtinger's inequality 4417: 4327: 4131: 3943: 3850: 3590:coordinate functions. 3558:real projective space 3262: 2979: 2769: 2562: 2355:self-adjoint operator 2341:for nonzero integers 2329:, the eigenvalues of 2252:converges to zero as 2234:converges to zero as 2147: 2076: 1736: 1512: 1228: 1153: 1081: 1016: 931: 741:Friedrichs inequality 675: 469: 243: 4874:Theorems in analysis 4378: 4146: 3962: 3873: 3760: 3732:[0, 2π] 3384:Riemannian manifolds 3030: 2845: 2623: 2576:integration by parts 2364: 2293:denote the function 2091: 1852: 1542: 1330: 1300:Integration by parts 1096: 964: 787: 546: 340: 109: 40:Wirtinger inequality 4444:, which amounts to 4347:can be replaced by 4249: 4166: 4016: 3896: 3780: 3366:In the language of 3200: 3184: 3169: 3104: 3084: 2945: 2932: 2862: 2723: 2708: 2662: 2514: 2443: 2381: 2264:Functional analysis 2108: 2015: 1948: 1899: 1823:for every function 1694: 1605: 1559: 1219: 1201: 1116: 1072: 1054: 984: 955:Parseval's identity 943:is zero means that 754:change of variables 735:, with the optimal 733:Poincaré inequality 633: 563: 427: 357: 201: 126: 56:Poincaré inequality 16:Theorem in analysis 4412: 4322: 4232: 4149: 4126: 3999: 3938: 3879: 3845: 3763: 3374:and corresponding 3257: 3188: 3170: 3155: 3092: 3070: 2974: 2933: 2918: 2848: 2764: 2709: 2694: 2648: 2605:which converge in 2557: 2500: 2429: 2367: 2357:, it follows that 2142: 2094: 2071: 2001: 1934: 1885: 1731: 1680: 1591: 1545: 1507: 1223: 1205: 1187: 1099: 1076: 1058: 1040: 967: 926: 843: 670: 619: 549: 464: 413: 343: 238: 187: 112: 4753:Littlewood, J. E. 4677:978-0-387-70913-0 4626:, Theorem II.5.4. 4401: 3985: 3834: 3392:Riemannian circle 3368:spectral geometry 3362:Spectral geometry 2916: 2498: 2353:is a bounded and 1993: 1836:Hölder inequality 1460: 916: 915: 880: 879: 828: 813: 737:Poincaré constant 729:spectral geometry 617: 411: 288:for some numbers 185: 46:. It was used by 44:Wilhelm Wirtinger 4881: 4864:Fourier analysis 4850: 4814: 4784: 4744: 4697: 4643: 4633: 4627: 4621: 4612: 4606: 4600: 4594: 4588: 4582: 4576: 4570: 4564: 4558: 4549: 4543: 4523: 4511: 4502: 4493: 4465: 4443: 4421: 4419: 4418: 4413: 4402: 4400: 4392: 4391: 4382: 4370: 4367:, so as to make 4366: 4363:for some number 4362: 4346: 4331: 4329: 4328: 4323: 4315: 4309: 4308: 4302: 4301: 4280: 4279: 4264: 4256: 4255: 4248: 4240: 4225: 4219: 4218: 4213: 4212: 4181: 4173: 4172: 4165: 4157: 4135: 4133: 4132: 4127: 4122: 4116: 4115: 4100: 4074: 4073: 4058: 4047: 4046: 4031: 4023: 4022: 4015: 4007: 3986: 3984: 3976: 3975: 3966: 3954: 3947: 3945: 3944: 3939: 3931: 3916: 3895: 3887: 3861: 3854: 3852: 3851: 3846: 3841: 3835: 3833: 3832: 3817: 3806: 3805: 3790: 3782: 3779: 3771: 3752: 3746: 3734: 3733: 3728: 3699: 3684: 3675: 3659: 3637: 3633: 3630:with itself) is 3629: 3625: 3621: 3614: 3608: 3596: 3589: 3582: 3578: 3570: 3547: 3543: 3542: 3540: 3539: 3534: 3531: 3516: 3515: 3513: 3512: 3507: 3504: 3496: 3495: 3483: 3479: 3478: 3476: 3475: 3470: 3467: 3452: 3451: 3449: 3448: 3443: 3440: 3432: 3431: 3419: 3418: 3416: 3415: 3410: 3407: 3399: 3350: 3347:for some number 3346: 3324: 3313: 3291: 3283: 3266: 3264: 3263: 3258: 3253: 3244: 3238: 3237: 3222: 3221: 3196: 3183: 3178: 3168: 3163: 3148: 3142: 3141: 3126: 3125: 3100: 3091: 3090: 3083: 3078: 3057: 3056: 3022: 3016: 3012: 3001: 2997: 2983: 2981: 2980: 2975: 2967: 2961: 2960: 2941: 2931: 2926: 2917: 2915: 2914: 2902: 2894: 2888: 2887: 2872: 2871: 2861: 2856: 2837: 2821: 2808: 2787: 2773: 2771: 2770: 2765: 2757: 2748: 2733: 2732: 2722: 2717: 2707: 2702: 2687: 2672: 2671: 2661: 2656: 2635: 2634: 2615: 2608: 2604: 2603: 2598: 2587: 2586: 2581: 2573: 2566: 2564: 2563: 2558: 2553: 2547: 2546: 2531: 2513: 2508: 2499: 2497: 2496: 2484: 2476: 2442: 2437: 2428: 2427: 2409: 2403: 2402: 2380: 2375: 2352: 2348: 2344: 2340: 2332: 2324: 2313: 2302: 2301: 2296: 2292: 2285: 2284: 2279: 2275: 2271: 2259: 2255: 2251: 2237: 2233: 2215: 2211: 2210: 2208: 2207: 2202: 2199: 2186: 2182: 2173: 2171: 2170: 2165: 2162: 2151: 2149: 2148: 2143: 2138: 2132: 2131: 2116: 2107: 2102: 2080: 2078: 2077: 2072: 2067: 2066: 2062: 2053: 2049: 2045: 2039: 2038: 2023: 2014: 2009: 1994: 1989: 1981: 1975: 1961: 1953: 1947: 1942: 1930: 1926: 1922: 1907: 1898: 1893: 1876: 1859: 1844: 1833: 1822: 1815: 1808: 1791: 1787: 1765: 1740: 1738: 1737: 1732: 1724: 1718: 1717: 1702: 1693: 1688: 1673: 1667: 1666: 1661: 1660: 1620: 1612: 1611: 1604: 1599: 1584: 1578: 1577: 1558: 1553: 1534: 1516: 1514: 1513: 1508: 1503: 1502: 1487: 1486: 1468: 1467: 1461: 1459: 1448: 1443: 1442: 1427: 1416: 1415: 1410: 1409: 1369: 1361: 1360: 1351: 1350: 1322: 1311: 1307: 1291: 1259: 1252: 1232: 1230: 1229: 1224: 1218: 1213: 1200: 1195: 1183: 1182: 1172: 1167: 1146: 1140: 1139: 1124: 1115: 1107: 1085: 1083: 1082: 1077: 1071: 1066: 1053: 1048: 1035: 1030: 1009: 1003: 1002: 983: 975: 952: 942: 935: 933: 932: 927: 922: 918: 917: 911: 910: 896: 894: 893: 881: 875: 874: 860: 858: 857: 842: 824: 823: 814: 806: 775: 771: 759: 722: 719:for some number 718: 717: 715: 714: 709: 706: 679: 677: 676: 671: 663: 657: 656: 641: 632: 627: 618: 616: 615: 606: 605: 596: 588: 582: 581: 562: 557: 535: 534: 525: 516: 513:for some number 512: 511: 509: 508: 503: 500: 473: 471: 470: 465: 457: 451: 450: 435: 426: 421: 412: 410: 409: 400: 399: 390: 382: 376: 375: 356: 351: 329: 314: 313: 304: 295: 291: 287: 286: 284: 283: 278: 275: 247: 245: 244: 239: 231: 225: 224: 209: 200: 195: 186: 184: 183: 182: 169: 168: 159: 151: 145: 144: 125: 120: 98: 83: 82: 73: 4889: 4888: 4884: 4883: 4882: 4880: 4879: 4878: 4854: 4853: 4819:Stein, Elias M. 4817: 4787: 4747: 4725: 4700: 4678: 4650: 4647: 4646: 4638:, Section 7.7; 4634: 4630: 4622: 4615: 4611:, Section II.2. 4607: 4603: 4595: 4591: 4587:, Chapter IV.2. 4583: 4579: 4571: 4567: 4559: 4552: 4544: 4535: 4530: 4513: 4510: 4504: 4501: 4495: 4492: 4481: 4467: 4459: 4445: 4426: 4393: 4383: 4376: 4375: 4368: 4364: 4348: 4336: 4293: 4271: 4257: 4206: 4174: 4144: 4143: 4093: 4065: 4051: 4038: 4024: 3977: 3967: 3960: 3959: 3952: 3909: 3871: 3870: 3859: 3824: 3810: 3797: 3783: 3758: 3757: 3748: 3736: 3731: 3730: 3718: 3707: 3698: 3689: 3680: 3674: 3664: 3655: 3648:Euclidean space 3635: 3631: 3627: 3623: 3619: 3610: 3602: 3594: 3584: 3580: 3576: 3565: 3545: 3535: 3532: 3526: 3525: 3523: 3518: 3508: 3505: 3502: 3501: 3499: 3498: 3489: 3488: 3481: 3471: 3468: 3462: 3461: 3459: 3454: 3444: 3441: 3438: 3437: 3435: 3434: 3425: 3424: 3411: 3408: 3405: 3404: 3402: 3401: 3395: 3364: 3356:function spaces 3348: 3330: 3315: 3296: 3289: 3274: 3213: 3117: 3048: 3028: 3027: 3018: 3014: 3011: 3003: 2999: 2996: 2988: 2952: 2906: 2879: 2863: 2843: 2842: 2835: 2823: 2819: 2810: 2806: 2797: 2789: 2786: 2778: 2724: 2663: 2626: 2621: 2620: 2610: 2606: 2601: 2600: 2597: 2589: 2584: 2583: 2579: 2571: 2538: 2524: 2488: 2416: 2394: 2362: 2361: 2350: 2346: 2342: 2334: 2330: 2315: 2304: 2299: 2298: 2294: 2287: 2282: 2281: 2277: 2273: 2269: 2266: 2257: 2253: 2239: 2235: 2221: 2218:squeeze theorem 2213: 2203: 2200: 2197: 2196: 2194: 2188: 2184: 2166: 2163: 2160: 2159: 2157: 2156: 2123: 2109: 2089: 2088: 2030: 2016: 2000: 1996: 1995: 1954: 1900: 1884: 1880: 1850: 1849: 1839: 1824: 1817: 1810: 1796: 1789: 1771: 1745: 1709: 1695: 1654: 1613: 1569: 1540: 1539: 1525: 1478: 1452: 1434: 1420: 1403: 1362: 1342: 1328: 1327: 1313: 1309: 1305: 1302: 1286: 1275: 1261: 1254: 1249: 1242: 1237: 1174: 1131: 1117: 1094: 1093: 994: 962: 961: 950: 944: 940: 897: 885: 861: 849: 848: 844: 815: 785: 784: 773: 769: 766: 757: 749: 720: 710: 707: 701: 700: 698: 685: 648: 634: 607: 597: 573: 544: 543: 528: 527: 523: 514: 504: 501: 495: 494: 492: 479: 442: 428: 401: 391: 367: 338: 337: 316: 307: 306: 302: 293: 289: 279: 276: 269: 268: 266: 253: 216: 202: 174: 170: 160: 136: 107: 106: 85: 76: 75: 71: 64: 17: 12: 11: 5: 4887: 4885: 4877: 4876: 4871: 4866: 4856: 4855: 4852: 4851: 4815: 4785: 4745: 4723: 4707:Academic Press 4698: 4676: 4645: 4644: 4628: 4613: 4601: 4589: 4577: 4565: 4550: 4548:, Section 7.7. 4532: 4531: 4529: 4526: 4508: 4499: 4490: 4479: 4457: 4423: 4422: 4411: 4408: 4405: 4399: 4396: 4390: 4386: 4333: 4332: 4321: 4318: 4314: 4307: 4300: 4296: 4292: 4289: 4286: 4283: 4278: 4274: 4270: 4267: 4263: 4260: 4254: 4247: 4244: 4239: 4235: 4231: 4228: 4224: 4217: 4211: 4205: 4202: 4199: 4196: 4193: 4190: 4187: 4184: 4180: 4177: 4171: 4164: 4161: 4156: 4152: 4137: 4136: 4125: 4121: 4114: 4109: 4106: 4103: 4099: 4096: 4092: 4089: 4086: 4083: 4080: 4077: 4072: 4068: 4064: 4061: 4057: 4054: 4050: 4045: 4041: 4037: 4034: 4030: 4027: 4021: 4014: 4011: 4006: 4002: 3998: 3995: 3992: 3989: 3983: 3980: 3974: 3970: 3949: 3948: 3937: 3934: 3930: 3925: 3922: 3919: 3915: 3912: 3908: 3905: 3902: 3899: 3894: 3891: 3886: 3882: 3878: 3864:Stokes theorem 3856: 3855: 3844: 3840: 3831: 3827: 3823: 3820: 3816: 3813: 3809: 3804: 3800: 3796: 3793: 3789: 3786: 3778: 3775: 3770: 3766: 3706: 3703: 3702: 3701: 3693: 3677: 3668: 3640: 3639: 3616: 3591: 3550: 3549: 3485: 3421: 3376:eigenfunctions 3363: 3360: 3268: 3267: 3256: 3252: 3247: 3243: 3236: 3231: 3228: 3225: 3220: 3216: 3212: 3209: 3206: 3203: 3199: 3195: 3191: 3187: 3182: 3177: 3173: 3167: 3162: 3158: 3154: 3151: 3147: 3140: 3135: 3132: 3129: 3124: 3120: 3116: 3113: 3110: 3107: 3103: 3099: 3095: 3089: 3082: 3077: 3073: 3069: 3066: 3063: 3060: 3055: 3051: 3047: 3044: 3041: 3038: 3035: 3007: 2992: 2985: 2984: 2973: 2970: 2966: 2959: 2955: 2951: 2948: 2944: 2940: 2936: 2930: 2925: 2921: 2913: 2909: 2905: 2900: 2897: 2893: 2886: 2882: 2878: 2875: 2870: 2866: 2860: 2855: 2851: 2831: 2815: 2802: 2793: 2782: 2775: 2774: 2763: 2760: 2756: 2751: 2747: 2742: 2739: 2736: 2731: 2727: 2721: 2716: 2712: 2706: 2701: 2697: 2693: 2690: 2686: 2681: 2678: 2675: 2670: 2666: 2660: 2655: 2651: 2647: 2644: 2641: 2638: 2633: 2629: 2616:. Then define 2593: 2585:[0, 1] 2568: 2567: 2556: 2552: 2545: 2541: 2537: 2534: 2530: 2527: 2523: 2520: 2517: 2512: 2507: 2503: 2495: 2491: 2487: 2482: 2479: 2475: 2470: 2467: 2464: 2461: 2458: 2455: 2452: 2449: 2446: 2441: 2436: 2432: 2426: 2423: 2419: 2415: 2412: 2408: 2401: 2397: 2393: 2390: 2387: 2384: 2379: 2374: 2370: 2300:[0, 1] 2283:[0, 1] 2265: 2262: 2153: 2152: 2141: 2137: 2130: 2126: 2122: 2119: 2115: 2112: 2106: 2101: 2097: 2082: 2081: 2070: 2065: 2061: 2057: 2052: 2048: 2044: 2037: 2033: 2029: 2026: 2022: 2019: 2013: 2008: 2004: 1999: 1992: 1987: 1984: 1980: 1974: 1970: 1967: 1964: 1960: 1957: 1952: 1946: 1941: 1937: 1933: 1929: 1925: 1921: 1916: 1913: 1910: 1906: 1903: 1897: 1892: 1888: 1883: 1879: 1875: 1871: 1868: 1865: 1862: 1858: 1742: 1741: 1730: 1727: 1723: 1716: 1712: 1708: 1705: 1701: 1698: 1692: 1687: 1683: 1679: 1676: 1672: 1665: 1659: 1653: 1650: 1647: 1644: 1641: 1638: 1635: 1632: 1629: 1626: 1623: 1619: 1616: 1610: 1603: 1598: 1594: 1590: 1587: 1583: 1576: 1572: 1568: 1565: 1562: 1557: 1552: 1548: 1518: 1517: 1506: 1501: 1496: 1493: 1490: 1485: 1481: 1477: 1474: 1471: 1466: 1458: 1455: 1451: 1446: 1441: 1437: 1433: 1430: 1426: 1423: 1419: 1414: 1408: 1402: 1399: 1396: 1393: 1390: 1387: 1384: 1381: 1378: 1375: 1372: 1368: 1365: 1359: 1354: 1349: 1345: 1341: 1338: 1335: 1301: 1298: 1284: 1273: 1247: 1240: 1234: 1233: 1222: 1217: 1212: 1208: 1204: 1199: 1194: 1190: 1186: 1181: 1177: 1171: 1166: 1163: 1160: 1156: 1152: 1149: 1145: 1138: 1134: 1130: 1127: 1123: 1120: 1114: 1111: 1106: 1102: 1087: 1086: 1075: 1070: 1065: 1061: 1057: 1052: 1047: 1043: 1039: 1034: 1029: 1026: 1023: 1019: 1015: 1012: 1008: 1001: 997: 993: 990: 987: 982: 979: 974: 970: 948: 937: 936: 925: 921: 914: 909: 906: 903: 900: 892: 888: 884: 878: 873: 870: 867: 864: 856: 852: 847: 841: 838: 835: 831: 827: 822: 818: 812: 809: 804: 801: 798: 795: 792: 765: 764:Fourier series 762: 748: 745: 725: 724: 682: 681: 680: 669: 666: 662: 655: 651: 647: 644: 640: 637: 631: 626: 622: 614: 610: 604: 600: 594: 591: 587: 580: 576: 572: 569: 566: 561: 556: 552: 538: 537: 519: 518: 476: 475: 474: 463: 460: 456: 449: 445: 441: 438: 434: 431: 425: 420: 416: 408: 404: 398: 394: 388: 385: 381: 374: 370: 366: 363: 360: 355: 350: 346: 332: 331: 298: 297: 250: 249: 248: 237: 234: 230: 223: 219: 215: 212: 208: 205: 199: 194: 190: 181: 177: 173: 167: 163: 157: 154: 150: 143: 139: 135: 132: 129: 124: 119: 115: 101: 100: 63: 60: 28: 27: 15: 13: 10: 9: 6: 4: 3: 2: 4886: 4875: 4872: 4870: 4867: 4865: 4862: 4861: 4859: 4848: 4844: 4840: 4836: 4832: 4828: 4824: 4820: 4816: 4812: 4808: 4804: 4800: 4799: 4794: 4790: 4786: 4782: 4778: 4774: 4770: 4766: 4762: 4758: 4754: 4750: 4746: 4742: 4738: 4734: 4730: 4726: 4724:0-12-170640-0 4720: 4716: 4712: 4708: 4704: 4699: 4695: 4691: 4687: 4683: 4679: 4673: 4669: 4665: 4661: 4657: 4653: 4649: 4648: 4641: 4637: 4632: 4629: 4625: 4620: 4618: 4614: 4610: 4605: 4602: 4599:, p. 36. 4598: 4593: 4590: 4586: 4581: 4578: 4574: 4569: 4566: 4562: 4557: 4555: 4551: 4547: 4542: 4540: 4538: 4534: 4527: 4525: 4521: 4517: 4507: 4498: 4489: 4485: 4478: 4474: 4470: 4463: 4456: 4452: 4448: 4441: 4437: 4433: 4429: 4409: 4406: 4403: 4397: 4394: 4388: 4384: 4374: 4373: 4372: 4360: 4356: 4352: 4344: 4340: 4319: 4316: 4298: 4290: 4284: 4281: 4276: 4268: 4261: 4258: 4245: 4242: 4237: 4233: 4229: 4226: 4215: 4200: 4194: 4191: 4185: 4178: 4175: 4162: 4159: 4154: 4150: 4142: 4141: 4140: 4123: 4104: 4097: 4094: 4087: 4081: 4078: 4075: 4070: 4062: 4055: 4052: 4048: 4043: 4035: 4028: 4025: 4012: 4009: 4004: 4000: 3996: 3993: 3990: 3987: 3981: 3978: 3972: 3968: 3958: 3957: 3956: 3935: 3932: 3920: 3913: 3910: 3903: 3897: 3892: 3889: 3884: 3880: 3876: 3869: 3868: 3867: 3865: 3858:and the area 3842: 3829: 3821: 3814: 3811: 3807: 3802: 3794: 3787: 3784: 3776: 3773: 3768: 3764: 3756: 3755: 3754: 3751: 3744: 3740: 3726: 3722: 3717:in 1901. Let 3716: 3715:Adolf Hurwitz 3712: 3704: 3696: 3692: 3688: 3683: 3678: 3672: 3667: 3663: 3658: 3653: 3652: 3651: 3649: 3645: 3617: 3613: 3606: 3600: 3592: 3587: 3574: 3573: 3572: 3568: 3563: 3559: 3555: 3538: 3530: 3521: 3511: 3493: 3486: 3474: 3466: 3457: 3447: 3429: 3422: 3414: 3398: 3393: 3389: 3388: 3387: 3385: 3381: 3377: 3373: 3369: 3361: 3359: 3358:in question. 3357: 3352: 3345: 3341: 3337: 3333: 3329:, shows that 3328: 3322: 3318: 3311: 3307: 3303: 3299: 3295: 3287: 3281: 3277: 3271: 3254: 3245: 3226: 3218: 3214: 3210: 3204: 3197: 3193: 3189: 3180: 3175: 3171: 3165: 3160: 3156: 3152: 3149: 3130: 3122: 3118: 3114: 3108: 3101: 3097: 3093: 3080: 3075: 3071: 3067: 3061: 3053: 3049: 3045: 3039: 3033: 3026: 3025: 3024: 3021: 3013:converges in 3010: 3006: 2995: 2991: 2971: 2968: 2957: 2949: 2942: 2938: 2934: 2928: 2923: 2919: 2911: 2907: 2903: 2898: 2895: 2884: 2876: 2868: 2864: 2858: 2853: 2849: 2841: 2840: 2839: 2834: 2830: 2826: 2818: 2814: 2805: 2801: 2796: 2792: 2785: 2781: 2761: 2758: 2749: 2737: 2729: 2725: 2719: 2714: 2710: 2704: 2699: 2695: 2691: 2688: 2676: 2668: 2664: 2658: 2653: 2649: 2645: 2639: 2631: 2627: 2619: 2618: 2617: 2613: 2596: 2592: 2577: 2554: 2543: 2535: 2528: 2521: 2518: 2510: 2505: 2501: 2493: 2489: 2485: 2480: 2477: 2465: 2459: 2456: 2450: 2444: 2439: 2434: 2430: 2424: 2421: 2417: 2413: 2410: 2399: 2391: 2385: 2382: 2377: 2372: 2368: 2360: 2359: 2358: 2356: 2338: 2328: 2322: 2318: 2311: 2307: 2290: 2263: 2261: 2256:converges to 2250: 2246: 2242: 2232: 2228: 2224: 2219: 2206: 2192: 2180: 2176: 2169: 2139: 2128: 2120: 2113: 2110: 2104: 2099: 2095: 2087: 2086: 2085: 2068: 2063: 2059: 2055: 2050: 2046: 2035: 2027: 2020: 2017: 2011: 2006: 2002: 1997: 1990: 1985: 1982: 1965: 1958: 1955: 1944: 1939: 1935: 1931: 1927: 1923: 1911: 1904: 1901: 1895: 1890: 1886: 1881: 1877: 1866: 1860: 1848: 1847: 1846: 1842: 1837: 1831: 1827: 1820: 1813: 1807: 1803: 1799: 1793: 1786: 1782: 1778: 1774: 1769: 1764: 1760: 1756: 1752: 1748: 1728: 1725: 1714: 1706: 1699: 1696: 1690: 1685: 1681: 1677: 1674: 1663: 1651: 1648: 1645: 1639: 1633: 1630: 1624: 1617: 1614: 1601: 1596: 1592: 1588: 1585: 1574: 1566: 1560: 1555: 1550: 1546: 1538: 1537: 1536: 1532: 1528: 1523: 1504: 1494: 1491: 1488: 1483: 1475: 1469: 1456: 1453: 1449: 1444: 1439: 1431: 1424: 1421: 1417: 1412: 1400: 1397: 1394: 1388: 1382: 1379: 1373: 1366: 1363: 1352: 1347: 1339: 1333: 1326: 1325: 1324: 1320: 1316: 1299: 1297: 1295: 1290: 1283: 1279: 1272: 1268: 1264: 1257: 1250: 1243: 1215: 1210: 1206: 1202: 1197: 1192: 1188: 1179: 1175: 1164: 1161: 1158: 1154: 1150: 1147: 1136: 1128: 1121: 1118: 1112: 1109: 1104: 1100: 1092: 1091: 1090: 1068: 1063: 1059: 1055: 1050: 1045: 1041: 1027: 1024: 1021: 1017: 1013: 1010: 999: 991: 985: 980: 977: 972: 968: 960: 959: 958: 956: 947: 923: 919: 912: 907: 904: 901: 898: 890: 886: 882: 876: 871: 868: 865: 862: 854: 850: 845: 839: 836: 833: 829: 825: 820: 816: 810: 807: 802: 796: 790: 783: 782: 781: 779: 763: 761: 755: 746: 744: 742: 738: 734: 730: 713: 705: 696: 692: 688: 683: 667: 664: 653: 645: 638: 635: 629: 624: 620: 612: 608: 602: 598: 592: 589: 578: 570: 564: 559: 554: 550: 542: 541: 540: 539: 532: 521: 520: 507: 499: 490: 486: 482: 477: 461: 458: 447: 439: 432: 429: 423: 418: 414: 406: 402: 396: 392: 386: 383: 372: 364: 358: 353: 348: 344: 336: 335: 334: 333: 327: 323: 319: 311: 300: 299: 282: 273: 264: 260: 256: 251: 235: 232: 221: 213: 206: 203: 197: 192: 188: 179: 175: 171: 165: 161: 155: 152: 141: 133: 127: 122: 117: 113: 105: 104: 103: 102: 96: 92: 88: 80: 69: 68: 67: 61: 59: 57: 53: 49: 48:Adolf Hurwitz 45: 41: 37: 33: 26: 24: 19: 18: 4869:Inequalities 4826: 4823:Weiss, Guido 4802: 4796: 4761:Inequalities 4760: 4749:Hardy, G. H. 4702: 4655: 4652:Brezis, Haim 4640:Hurwitz 1901 4631: 4604: 4592: 4580: 4568: 4519: 4515: 4505: 4496: 4487: 4486:– α) + 4483: 4476: 4472: 4468: 4461: 4454: 4450: 4446: 4439: 4435: 4431: 4427: 4424: 4358: 4354: 4350: 4342: 4338: 4334: 4138: 3950: 3857: 3749: 3742: 3738: 3724: 3720: 3708: 3694: 3690: 3681: 3670: 3665: 3656: 3644:metric balls 3641: 3611: 3604: 3599:covering map 3585: 3566: 3551: 3536: 3528: 3519: 3509: 3491: 3472: 3464: 3455: 3445: 3427: 3412: 3396: 3365: 3353: 3343: 3339: 3335: 3331: 3320: 3316: 3309: 3305: 3301: 3297: 3279: 3275: 3272: 3269: 3019: 3008: 3004: 2993: 2989: 2986: 2832: 2828: 2824: 2816: 2812: 2803: 2799: 2794: 2790: 2783: 2779: 2776: 2611: 2594: 2590: 2569: 2336: 2320: 2316: 2309: 2305: 2288: 2267: 2248: 2244: 2240: 2230: 2226: 2222: 2204: 2190: 2178: 2174: 2167: 2154: 2083: 1840: 1829: 1825: 1818: 1811: 1805: 1801: 1797: 1794: 1784: 1780: 1776: 1772: 1762: 1758: 1754: 1750: 1746: 1743: 1533:(π) = 0 1530: 1526: 1519: 1318: 1314: 1303: 1288: 1281: 1277: 1270: 1266: 1262: 1255: 1245: 1238: 1235: 1088: 945: 938: 767: 750: 736: 726: 711: 703: 694: 690: 686: 530: 505: 497: 488: 484: 480: 325: 321: 317: 309: 280: 271: 262: 258: 254: 94: 90: 86: 78: 65: 39: 32:mathematical 29: 20: 4805:: 401–403. 4789:Hurwitz, A. 4624:Chavel 1984 4609:Chavel 1984 4597:Chavel 1984 4573:Chavel 1984 4561:Brezis 2011 1535:then shows 4858:Categories 4847:0232.42007 4811:32.0386.01 4781:0047.05302 4741:0551.53001 4694:1220.46002 4528:References 3394:of length 3372:eigenvalue 3342:cos π 3288:says that 2777:Then each 2349:. Because 4757:Pólya, G. 4466:and then 4464:– α) 4404:≥ 4398:π 4282:− 4246:π 4234:∫ 4163:π 4151:∫ 4013:π 4001:∫ 3988:− 3982:π 3893:π 3881:∫ 3877:− 3777:π 3765:∫ 3211:− 3172:∫ 3157:∫ 3153:− 3115:− 3072:∫ 3046:− 2920:∫ 2908:π 2899:≤ 2850:∫ 2711:∫ 2696:∫ 2692:− 2650:∫ 2502:∫ 2490:π 2431:∫ 2422:− 2418:π 2414:≤ 2369:∫ 2105:π 2096:∫ 2003:∫ 1986:≤ 1936:∫ 1932:≤ 1887:∫ 1691:π 1682:∫ 1649:⁡ 1631:− 1602:π 1593:∫ 1556:π 1547:∫ 1492:⁡ 1445:− 1398:⁡ 1380:− 1170:∞ 1155:∑ 1113:π 1101:∫ 1033:∞ 1018:∑ 981:π 969:∫ 913:π 902:⁡ 877:π 866:⁡ 837:≥ 830:∑ 621:∫ 609:π 593:≤ 551:∫ 415:∫ 403:π 387:≤ 345:∫ 274:− α) 189:∫ 176:π 156:≤ 114:∫ 34:field of 4825:(1971). 4791:(1901). 4759:(1952). 4660:Springer 4654:(2011). 4262:′ 4179:′ 4098:′ 4056:′ 4029:′ 3914:′ 3815:′ 3788:′ 3735:so that 3490:[0, 3426:[0, 3323:′(1) = 0 3198:′ 3102:′ 2943:′ 2807:′(1) = 0 2570:for all 2529:′ 2323:′(1) = 0 2114:′ 2021:′ 1959:′ 1905:′ 1821:= π 1700:′ 1618:′ 1425:′ 1367:′ 1253:for all 1122:′ 776:. Since 639:′ 529:[0, 433:′ 308:[0, 270:2π( 207:′ 77:[0, 36:analysis 4839:0304972 4773:0046395 4733:0768584 4686:2759829 3628:2π 3541:⁠ 3524:⁠ 3514:⁠ 3500:⁠ 3477:⁠ 3460:⁠ 3450:⁠ 3436:⁠ 3417:⁠ 3406:4π 3403:⁠ 3378:of the 3319:′(0) = 2798:′(0) = 2339:π) 2319:′(0) = 2209:⁠ 2195:⁠ 2172:⁠ 2158:⁠ 1843:(0) = 0 774:2π 716:⁠ 699:⁠ 510:⁠ 493:⁠ 285:⁠ 267:⁠ 62:Theorem 30:In the 4845:  4837:  4809:  4779:  4771:  4739:  4731:  4721:  4692:  4684:  4674:  3673:− 2)/2 3554:sphere 3527:π 3503:π 3463:π 3439:π 2602:(0, 1) 2347:π 2272:to be 2258:π 2247:) cot 2229:) cot 1804:) cot 1761:) cot 1529:(0) = 1310:π 1308:to be 772:to be 747:Proofs 702:π 496:π 330:. Then 320:(0) = 294:α 99:. Then 89:(0) = 38:, the 4442:) = 0 3866:) by 3562:torus 3560:, or 3494:] 3430:] 3314:with 3312:) = 0 2308:′′ + 2220:that 2193:< 1845:that 1770:) is 953:. By 533:] 328:) = 0 315:with 312:] 81:] 4719:ISBN 4672:ISBN 4503:and 4482:cos( 4475:) = 4460:sin( 4453:) = 4434:) + 3522:cos 3458:sin 3338:) = 3304:) + 2333:are 2314:and 2189:cot 1838:and 1816:and 1783:sin 1779:) = 1753:) = 1287:cos 1276:sin 1269:) = 1089:and 697:cos 693:) = 522:Let 491:sin 487:) = 301:Let 292:and 265:sin 261:) = 70:Let 4843:Zbl 4807:JFM 4803:132 4777:Zbl 4737:Zbl 4711:doi 4690:Zbl 4664:doi 3646:in 3607:+ 2 3588:+ 1 3569:= 1 3497:is 3433:is 3400:is 3300:′′( 3017:to 2998:by 2827:= − 2609:to 2582:on 2312:= 0 2297:on 2280:on 2183:as 1814:= 0 1646:cot 1489:cot 1395:cot 1258:≥ 2 1251:= 0 951:= 0 899:cos 863:sin 4860:: 4841:. 4835:MR 4833:. 4821:; 4801:. 4795:. 4775:. 4769:MR 4767:. 4755:; 4751:; 4735:. 4729:MR 4727:. 4717:. 4709:. 4688:. 4682:MR 4680:. 4670:. 4662:. 4616:^ 4553:^ 4536:^ 4518:, 4430:′( 4357:+ 4353:, 4341:, 3741:, 3723:, 3697:/2 3650:: 3556:, 3386:: 3351:. 2836:′′ 2820:′′ 2289:Tf 2260:. 1792:. 1749:′( 1296:. 1280:+ 1244:= 957:, 760:. 58:. 4849:. 4813:. 4783:. 4743:. 4713:: 4696:. 4666:: 4642:. 4522:) 4520:y 4516:x 4514:( 4509:2 4506:c 4500:1 4497:c 4491:2 4488:c 4484:t 4480:1 4477:c 4473:t 4471:( 4469:x 4462:t 4458:1 4455:c 4451:t 4449:( 4447:y 4440:t 4438:( 4436:y 4432:t 4428:x 4410:, 4407:A 4395:4 4389:2 4385:L 4369:y 4365:z 4361:) 4359:z 4355:y 4351:x 4349:( 4345:) 4343:y 4339:x 4337:( 4320:. 4317:t 4313:d 4306:) 4299:2 4295:) 4291:t 4288:( 4285:y 4277:2 4273:) 4269:t 4266:( 4259:y 4253:( 4243:2 4238:0 4230:+ 4227:t 4223:d 4216:2 4210:) 4204:) 4201:t 4198:( 4195:y 4192:+ 4189:) 4186:t 4183:( 4176:x 4170:( 4160:2 4155:0 4124:t 4120:d 4113:) 4108:) 4105:t 4102:( 4095:x 4091:) 4088:t 4085:( 4082:y 4079:2 4076:+ 4071:2 4067:) 4063:t 4060:( 4053:y 4049:+ 4044:2 4040:) 4036:t 4033:( 4026:x 4020:( 4010:2 4005:0 3997:= 3994:A 3991:2 3979:2 3973:2 3969:L 3953:L 3936:. 3933:t 3929:d 3924:) 3921:t 3918:( 3911:x 3907:) 3904:t 3901:( 3898:y 3890:2 3885:0 3860:A 3843:t 3839:d 3830:2 3826:) 3822:t 3819:( 3812:y 3808:+ 3803:2 3799:) 3795:t 3792:( 3785:x 3774:2 3769:0 3750:L 3745:) 3743:y 3739:x 3737:( 3727:) 3725:y 3721:x 3719:( 3700:. 3695:n 3691:J 3682:R 3676:. 3671:n 3669:( 3666:J 3657:R 3636:n 3632:1 3624:n 3620:n 3612:R 3605:n 3603:2 3595:n 3586:n 3581:n 3577:n 3567:n 3548:. 3546:c 3537:L 3533:/ 3529:x 3520:c 3510:L 3506:/ 3492:L 3484:. 3482:c 3473:L 3469:/ 3465:x 3456:c 3446:L 3442:/ 3428:L 3413:L 3409:/ 3397:L 3349:c 3344:x 3340:c 3336:x 3334:( 3332:y 3321:y 3317:y 3310:x 3308:( 3306:y 3302:x 3298:y 3290:y 3282:) 3280:x 3278:( 3276:y 3255:w 3251:d 3246:z 3242:d 3235:) 3230:) 3227:z 3224:( 3219:n 3215:g 3208:) 3205:z 3202:( 3194:n 3190:y 3186:( 3181:w 3176:0 3166:1 3161:0 3150:z 3146:d 3139:) 3134:) 3131:z 3128:( 3123:n 3119:g 3112:) 3109:z 3106:( 3098:n 3094:y 3088:( 3081:x 3076:0 3068:= 3065:) 3062:x 3059:( 3054:n 3050:y 3043:) 3040:x 3037:( 3034:y 3020:y 3015:L 3009:n 3005:y 3000:y 2994:n 2990:y 2972:. 2969:x 2965:d 2958:2 2954:) 2950:x 2947:( 2939:n 2935:y 2929:1 2924:0 2912:2 2904:1 2896:x 2892:d 2885:2 2881:) 2877:x 2874:( 2869:n 2865:y 2859:1 2854:0 2833:n 2829:y 2825:f 2817:n 2813:y 2811:− 2804:n 2800:y 2795:n 2791:y 2784:n 2780:y 2762:. 2759:w 2755:d 2750:z 2746:d 2741:) 2738:z 2735:( 2730:n 2726:g 2720:w 2715:0 2705:1 2700:0 2689:z 2685:d 2680:) 2677:z 2674:( 2669:n 2665:g 2659:x 2654:0 2646:= 2643:) 2640:x 2637:( 2632:n 2628:y 2614:′ 2612:y 2607:L 2595:n 2591:g 2580:y 2572:f 2555:x 2551:d 2544:2 2540:) 2536:x 2533:( 2526:) 2522:f 2519:T 2516:( 2511:1 2506:0 2494:2 2486:1 2481:= 2478:x 2474:d 2469:) 2466:x 2463:( 2460:f 2457:T 2454:) 2451:x 2448:( 2445:f 2440:1 2435:0 2425:2 2411:x 2407:d 2400:2 2396:) 2392:x 2389:( 2386:f 2383:T 2378:1 2373:0 2351:T 2343:k 2337:k 2335:( 2331:T 2321:u 2317:u 2310:f 2306:u 2295:u 2291:) 2278:f 2274:1 2270:L 2254:x 2249:x 2245:x 2243:( 2241:y 2236:x 2231:x 2227:x 2225:( 2223:y 2214:x 2205:x 2201:/ 2198:1 2191:x 2185:x 2181:) 2179:x 2177:( 2175:y 2168:x 2164:/ 2161:1 2140:x 2136:d 2129:2 2125:) 2121:x 2118:( 2111:y 2100:0 2069:, 2064:2 2060:/ 2056:1 2051:) 2047:x 2043:d 2036:2 2032:) 2028:x 2025:( 2018:y 2012:x 2007:0 1998:( 1991:x 1983:x 1979:d 1973:| 1969:) 1966:x 1963:( 1956:y 1951:| 1945:x 1940:0 1928:| 1924:x 1920:d 1915:) 1912:x 1909:( 1902:y 1896:x 1891:0 1882:| 1878:= 1874:| 1870:) 1867:x 1864:( 1861:y 1857:| 1841:y 1832:) 1830:x 1828:( 1826:y 1819:x 1812:x 1806:x 1802:x 1800:( 1798:y 1790:c 1785:x 1781:c 1777:x 1775:( 1773:y 1763:x 1759:x 1757:( 1755:y 1751:x 1747:y 1729:. 1726:x 1722:d 1715:2 1711:) 1707:x 1704:( 1697:y 1686:0 1678:= 1675:x 1671:d 1664:2 1658:) 1652:x 1643:) 1640:x 1637:( 1634:y 1628:) 1625:x 1622:( 1615:y 1609:( 1597:0 1589:+ 1586:x 1582:d 1575:2 1571:) 1567:x 1564:( 1561:y 1551:0 1531:y 1527:y 1505:. 1500:) 1495:x 1484:2 1480:) 1476:x 1473:( 1470:y 1465:( 1457:x 1454:d 1450:d 1440:2 1436:) 1432:x 1429:( 1422:y 1418:= 1413:2 1407:) 1401:x 1392:) 1389:x 1386:( 1383:y 1377:) 1374:x 1371:( 1364:y 1358:( 1353:+ 1348:2 1344:) 1340:x 1337:( 1334:y 1321:) 1319:x 1317:( 1315:y 1306:L 1289:x 1285:1 1282:b 1278:x 1274:1 1271:a 1267:x 1265:( 1263:y 1256:n 1248:n 1246:b 1241:n 1239:a 1221:) 1216:2 1211:n 1207:b 1203:+ 1198:2 1193:n 1189:a 1185:( 1180:2 1176:n 1165:1 1162:= 1159:n 1151:= 1148:x 1144:d 1137:2 1133:) 1129:x 1126:( 1119:y 1110:2 1105:0 1074:) 1069:2 1064:n 1060:b 1056:+ 1051:2 1046:n 1042:a 1038:( 1028:1 1025:= 1022:n 1014:= 1011:x 1007:d 1000:2 996:) 992:x 989:( 986:y 978:2 973:0 949:0 946:a 941:y 924:, 920:) 908:x 905:n 891:n 887:b 883:+ 872:x 869:n 855:n 851:a 846:( 840:1 834:n 826:+ 821:0 817:a 811:2 808:1 803:= 800:) 797:x 794:( 791:y 770:L 758:L 723:. 721:c 712:L 708:/ 704:x 695:c 691:x 689:( 687:y 668:. 665:x 661:d 654:2 650:) 646:x 643:( 636:y 630:L 625:0 613:2 603:2 599:L 590:x 586:d 579:2 575:) 571:x 568:( 565:y 560:L 555:0 531:L 524:y 517:. 515:c 506:L 502:/ 498:x 489:c 485:x 483:( 481:y 462:, 459:x 455:d 448:2 444:) 440:x 437:( 430:y 424:L 419:0 407:2 397:2 393:L 384:x 380:d 373:2 369:) 365:x 362:( 359:y 354:L 349:0 326:L 324:( 322:y 318:y 310:L 303:y 296:. 290:c 281:L 277:/ 272:x 263:c 259:x 257:( 255:y 236:, 233:x 229:d 222:2 218:) 214:x 211:( 204:y 198:L 193:0 180:2 172:4 166:2 162:L 153:x 149:d 142:2 138:) 134:x 131:( 128:y 123:L 118:0 97:) 95:L 93:( 91:y 87:y 79:L 72:y 25:.

Index

Wirtinger's inequality
mathematical
analysis
Wilhelm Wirtinger
Adolf Hurwitz
isoperimetric inequality
Poincaré inequality
spectral geometry
Poincaré inequality
Friedrichs inequality
change of variables
Dirichlet's conditions
Parseval's identity
trigonometric addition formulas
fundamental theorem of calculus
separation of variables
Hölder inequality
squeeze theorem
ordinary differential equations with constant coefficients
self-adjoint operator
integration by parts
calculus of variations
Euler–Lagrange equation
ordinary differential equations with constant coefficients
function spaces
spectral geometry
eigenvalue
eigenfunctions
Laplace–Beltrami operator
Riemannian manifolds

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