“…I], avoiding all mention of group representations. electromagnetic spectrum, 48, 156 elementary divisor theory, 72, 79 elementary row and column operations, 79 214, 317, 345, 354, 361 fractional linear transformation, 204, 213 function, 235, 247-250, 257, 258 geometry, 112, 147, 149, 153 integral, 200, 235, 247, 248 partial differential equation, 259 point, 213, 214, 240 elliptic fractional linear transformation, 213 energy level, 48, 58, 89, 119 Epstein zeta function, 33, 44, 58, 63, 64, 67, 69, Dedekind eta function, 230, 238, 264, 374 Euclid's fifth postulate, 112, 152 Euclid's second postulate, 112 Euclidean algorithm, 204 Euclidean group, 83, 90, 136, 148, 197, 367 even integral positive matrix, 243, 256 Ewald's method of theta functions, 87 excited state, 120 expectation or mean, 26, 191, 192 F Farey fractions, 315 fast Fourier transform or FFT, 31, 46, 90, 94 Féjer kernel, 3, 34 Feynman integrals, 319 Fibonacci tiling, 98 finite analogue of Euclidean distance, 90 finite Dirichlet polygon, 225 finite Eisenstein series, 291 finite element method, 54 finite Euclidean graph, 91 finite Euclidean space, 90 finite fundamental domain, 289 finite general linear group, 222, 292, 374 finite geodesic, 222 finite horocycle, 222 finite non-Euclidean distance, 222 finite rotation group, 222 finite simple group, 242 finite symmetric space, 90 finite tessellation, 225 finite trace formula, 374, 376 finite upper half-plane, 221, 223, 227, 289, 374 finite upper half-plane graph, 223 Fischer-Griess monster group, 242 Fourier analysis on symmetric space, 9, 117, 178 Fourier analysis on the fundamental domain, 31, 39, 333, 352 Fourier coefficient, 31, 40 Fourier inversion, see inversion of a transform Fourier series, 3, 4, 6, 13, 23, 31-37, 39-41, 43, Kontorovich-Lebedev transform, 142, 164, 168-171, 175-177 Korteweg-DeVries equation, 257 Korteweg-DeVries equation, 258 Kronecker limit formula, 264, 265 Kronecker symbol, 273 Kronecker theorem, 101 Laplace operator, 110-112, 114, 115, 117-119, 133, 136 Δ, Laplace operator,5, 18, 31, 36-38, 45, 56-58, 60, 92, 155, 164, 167, 170, 173, 184, 185, 187, 258-260, 263, 267, 270, 272, 273, 280, 283, 286, 288, 297, 317, 318, 320, 321, 323, 326, 328, 329, 331, 333, 337, 338, 340-342, 347, 360, 362, 365, 366 Δ, Laplace operator, 153 Laplace series of spherical harmonics, 118 lattice space, 367 least squares, method of, 51 Lebesgue dominated convergence theorem, 6, 11, 12, 188, 195 integrable function, 2, 15, 143, 349 integrable functions, L 1 (X), 7, 11, 12, 32, 127 integral, 11, 13 measurable function, 139 measure, 2, 25, 101, 322 square integrable functions, L 2 (X), 11 left G-action,154 Legendre function P s ,113, 114, 172-177, 191, 192, 224…”