Index A absolute stability, 189 absolute value, 83, 86 acceleration, 73, 478 accuracy, 184, 185, 190, 191 Adams method, 192, 193 add exponents, 9 addition formula, 87 adjacency matrix, 318, 320, 427 Airy’s equation, 130 albedo, 49 amplitude, 75, 82, 111 amplitude response, 34, 77 antisymmetric, 245, 323, 352, 409 applied mathematics, 316, 423, 487 arrows, 156, 318 associative law, 220 attractor, 170, 181 augmented matrix, 231, 259, 273, 280 autocorrelation, 480 autonomous, 57, 71, 157, 158, 160 average, 436, 440 B back substitution, 213, 264 backslash, 221 backward difference, 6, 12, 246, 415 backward Euler, 188, 189 bad news, 329 balance equation, 48, 118, 316, 424 balance of forces, 118 bank, 12, 40, 485 bar, 406, 408, 412, 455, 457 basis, 285, 289-291, 296, 338, 446, 447 beam, 469 beat, 128 bell-shaped curve, 16, 190, 458 Bernoulli equation, 61 Bessel function, 367, 460, 478 better notation, 113, 124, 125 big picture, 300, 303, 306, 400 Black-Scholes, 457 block matrix, 231, 237, 420 block multiplication, 226, 227 boundary conditions, 406, 411, 431, 457 boundary value problem, 406, 457, 470 box, 176 box function, 407, 439, 445, 469, 478, 488 Brauer, 180 C capacitance, 119 carbon, 46 carrying capacity, 53, 55, 61 Castillo-Chavez, 180 catalyst, 180 Cayley-Hamilton theorem, 348 cell phone, 44, 176 center, 161, 163, 174 centered difference, 6, 190 chain rule, 3, 4, 368, 371 change of variables, 365 chaos, 155, 181 characteristic equation, 90, 103, 108, 164 chebfun, 405 chemical engineering, 457 chess matrix, 311 Cholesky factorization, 403 circulant matrix, 205, 449, 486, 488 circular motion, 76, 351 closed-loop, 64 493 494 closest line, 387, 393 coefficient matrix, 199 cofactor, 331 column picture, 198, 206 column rank, 275, 322 column space, 254, 259, 278 column-times-row, 222, 226, 429 combination of columns, 199, 202 combination of eigenvectors, 329, 349, 356, 371, 374 commute, 221, 224 companion matrix, 164, 165, 167, 335, 354–356, 360, 369 competition, 53, 174 complete graph, 427, 428 complete solution, 1, 17, 18, 105, 106, 203, 211, 265, 274, 276 complex conjugate, 32, 87, 94, 379 complex eigenvalues, 166 complex exponential, 13, 432 complex Fourier series, 440 complex gain, 111 complex impedance, 120 complex matrix, 376 complex numbers, 31-33, 82-89 complex roots, 90, 163 complex solution, 36, 38, 39, 89 complex vector, 433 compound interest, 12, 185 computational mechanics, 372 computational science, 419, 447 concentration, 47, 180 condition number, 401 conductance matrix, 124, 385, 425, 426 conjugate transpose, 377 constant coefficients, 1, 98, 117, 432, 470, 487 constant diagonals, 482, 486, 487 constant source, 20 continuous, 154, 358 continuous interest, 44 convergence, 10, 196 convex, 73 convolution, 117, 136, 479-489 Index Convolution Rule, 476, 480, 484, 485 Cooley-Tukey, 451 cooling (Newton’s Law), 46 cosine series, 436 Counting Theorem, 267, 304, 314 Cramer’s Rule, 331 critical damping, 96, 100, 115 critical point, 170, 171, 182 cubic spline, 139 Current Law, 123, 317, 318 cyclic convolution, 485–487 D d’Alembert, 464, 467 damped frequency, 99, 105, 113 damped gain, 113 damping, 96, 112, 118, 122 damping ratio, 99, 113, 114 dashpot, 118 data, 401, 431 decay rate, 46, 437, 444, 456, 467 deconvolution, 485, 487 degree matrix, 318, 427, 429 delta function, 23, 28, 78, 97, 98, 407, 438, 439, 442, 458, 471 delta vector, 415, 447, 482 dependent, 288 dependent columns, 209 derivative rule, 141, 441, 476 determinant, 175, 228, 232, 326, 330, 332, 336, 347, 353, 402, 492 DFT, 432, 446, 449, 454, 485 diagonal matrix, 229, 398 diagonalizable, 363, 382 difference equation, 45, 52, 184, 188, 338 difference matrix, 240, 314, 405, 423 differential equation, 1, 40, 349 diffusion, 358, 456, 457 diagonalization, 337, 400 dimension, 44, 52, 267, 285, 291–293, 304, 322 dimensionless, 34, 99, 113, 124 direction field, 157 Discrete Cosine Transform (DCT), 454 Discrete Fourier Transform, (see DFT) 495 Index discrete sines, 405, 432, 454 displacements, 124 distributive law, 220 divergence, 417 dot product, 201, 214, 248, 377 double angle, 84 double pole, 145, 472 double root, 91, 92, 101 doublet, 151 doubling time, 46, 47 driving function, 77, 112, 476 dropoff curve, 57, 62, 157 E echelon matrix, 263, 266, 267 edge, 313, 423 eigenfunction, 408, 421, 455, 459, 467 eigenvalue, 164, 325, 326, 382 eigenvalue matrix, 337 eigenvector, 167, 325, 326, 382 eigenvector matrix, 337, 363 Einstein, 464 elapsed time, 98 elimination, 210, 212, 334 elimination matrix, 224, 229, 303 empty set, 293 energy, 396, 397, 409, 411, 424, 443 energy balance, 48 energy identity, 440, 444 enzyme, 180 epidemic, 179, 180 equal roots, 90, 92, 100 equilibrium, 417 error, 185, 186, 191, 193 error function, 458 error vector, 386, 394 Euler, 317 Euler equations, 176, 183 Euler’s Formula, 13, 82, 83, 450 Euler’s method, 185, 186, 189, 384 even permutation, 246 exact equations, 65 existence, 154, 196 exponential, 2, 7, 10, 25, 131, 362, 369 exponential response, 104, 108, 117 F factorization, 382, 490 farad, 122 Fast Fourier Transform, (see FFT) feedback, 64 FFT, 88, 432, 446, 447, 450, 451 fftw, 452 Fibonacci, 340, 345, 405 filter, 480 finite elements, 124, 373, 419, 430 finite speed, 463 first order, 164 flow graph, 452 football, 176, 178 force balance, 426 forced oscillation, 80, 105, 110 forward differences, 240 Four Fundamental Subspaces, 300, 303 Fourier coefficients, 435–437, 440 Fourier cosine series, 457 Fourier Integral Transform, 449 Fourier matrix, 85, 243, 446-448, 450 Fourier series, 419, 436, 439, 443, 455 Fourier sine series, 410, 434, 467 fourth order, 80, 93, 469 foxes, 172, 174 free column, 262 free variable, 262, 266, 269, 270, 274 free-free boundary conditions, 412 frequency, 31, 76, 79, 373, 466 frequency domain, 120, 145, 449, 480 frequency response, 36, 77, 432 frisbee, 176 full rank, 275-277, 281, 287, 385 function space, 293, 298, 433, 440, 480 fundamental matrix, 366, 371, 384 fundamental solution, 78, 81, 97, 117, 458 Fundamental Theorem, 5, 8, 42, 244, 304, 307, 400 G gain, 30, 33, 84, 104, 111 Gauss-Jordan, 230–232, 236, 283, 331 gene, 431 496 general solution, 280 generalized eigenvalues, 372 geometric series, 7 Gibbs phenomenon, 435, 436 gold, 153 Gompertz equation, 63 Google, 328 GPS, 464 gradient, 417, 421 graph, 313, 317, 318, 320, 416, 423 graph Laplacian, 316, 318, 423 Green’s function, 136, 482, 483 greenhouse effect, 49 grid, 416, 419, 429 ground a node, 424, 426 growth factor, 24, 40–42, 51, 97, 135, 482 growth rate, 2, 40, 364 H HKenon map, 181 Hadamard matrix, 243, 344 half-life, 46 harmonic motion, 75, 76, 79 harvesting, 59, 60, 62 hat function, 467 heat equation, 410, 455, 456 heat kernel, 457, 458, 460 Heaviside, 21, 477 Henry, 122 Hermitian matrix, 377 Hertz, 76 higher order, 93, 102, 105, 107, 117, 355 Hilbert space, 433 homogeneous, 17, 103 Hooke’s Law, 74, 374, 424 hyperplane, 207 I identity matrix, 201, 219 image, 484 imaginary eigenvalues, 331, 351 impedance, 39, 120, 121, 127 implicit, 67, 188 impulse, 23, 78 Index impulse response, 23, 24, 78, 97, 102, 117, 121, 136, 140, 150, 482 incidence matrix, 124, 313, 317, 320, 423 independence, 204 independent columns, 273, 276, 290, 322, 385, 391 independent eigenvectors, 362 independent rows, 273 inductance, 119 infection rate, 179 infinite series, 10, 13, 329, 369, 434, 455 inflection point, 54, 55 initial conditions, 2, 40, 73, 349, 457 initial values, 470, 483 inner product, 226, 323, 377, 409, 433 instability, 193 integrating factor, 19, 26, 41, 482 integration by parts, 248, 323, 409, 413, 431 interest rate, 12, 43, 485 intersection, 201, 258, 299 inverse matrix, 31, 228, 231, 482 inverse transform, 140, 446, 473, 477 invertible, 205, 213, 228, 290 isocline, 156, 159, 160 J Jacobian matrix, 171, 177 Jordan form, 357, 382, 383 Julia, 330 jump, 21, 474, 475 K key formula, 8, 19, 78, 112, 117, 135, 482 kinetic energy, 79 Kirchhoff’s Current Law, 316, 424 Kirchhoff’s Laws, 123, 272 Kirchhoff’s Voltage Law, 315 KKT matrix, 428 kron .A; B/, 420 L l’HOopital’s Rule, 43, 109 LAPACK, 242, 332 Laplace convolution, 481, 483 Laplace equation, 416, 417 497 Index Laplace transform, 121, 141-151, 470-478 Laplace’s equation, 418, 442, 443 Laplacian matrix, 318, 320, 424 law of mass action, 180 least squares, 385–387 left eigenvectors, 348 left nullspace, 300, 302 left-inverse, 228, 232, 242 length, 242 LiKenard, 182 linear combination, 199, 201, 254, 288 linear equation, 4, 17, 105, 134, 177, 349 linear shift-invariant, 459 linear time-invariant (LTI), 71, 349 linear transformation, 209 linearity, 221, 471 linearization, 172-179 linearly independent, 277, 287, 289 lobster trap, 159 logistic equation, 47, 53, 62, 157, 190 loop, 315–317 loop equation, 119, 123, 127 Lorenz equation, ix, 154, 181 Lotka-Volterra, 173 M magic matrix, 209 magnitude, 112 magnitude response, 34, 77 Markov matrix, 327, 329, 333, 382 mass action, 180 mass matrix, 372, 381 Mathematica, 194, 467 mathematical finance, 457 MATLAB, 191, 332, 372, 447, 451, 486 The single heading “Matrix” indexes the active life of linear algebra. Matrix . 1 2 1/, 246, 415, 454 adjacency, 318 antisymmetric, 352, 376 augmented, 230, 271, 278 circulant, 486, 488 companion, 164, 355, 360 complex, 376 difference, 240, 314, 405, 422 echelon, 266 eigenvalue, 337 eigenvector, 337, 363 elimination, 224, 229, 303 exponential, 14, 362, 368 factorizations, 382, 490 Fourier, 85, 243, 446, 447, 450 fundamental, 366 Hadamard, 243, 344 Hermitian, 377 identity, 201, 219 incidence, 124, 313, 314, 317, 423 inverse, 228, 231 invertible, 204, 213, 231, 290 Jacobian, 171, 177 KKT, 428 Laplacian, 318, 320, 424 Markov, 327, 333 orthogonal, 238, 247, 376 permutation, 241, 246, 299, 450 positive definite, 372, 385, 396 projection orthogonal, 238, 242, 247, 334, 376, 378, 382, 390, 394 rank one, 305, 382, 404 rectangular, 385 reflection, 247 rotation, 331 saddle-point, 428, 430 second difference, 414 semidefinite, 398, 412, 413 similar, 365, 370, 383 singular, 202, 326, 328, 492 skew-symmetric, 382 sparse, 223 stable, 352 stiffness, 124, 372, 385 symmetric, 238, 375, 409 Toeplitz, 480, 482 tridiagonal, 382, 454 unitary, 377 498 matrix multiplication, 219-223, 249 mean, 392, 395 mechanics, 74 mesh, 420 Michaelis-Menten, 180 minimum, 404 model problem, 40, 115, 374, 423 modulus, 32, 83 multiplication, 202, 219, 479 multiplicity, 93, 343 multiplier, 210, 214, 225 multistep method, 192 N natural frequency, 77, 99, 102, 466 network, 313-323, 416, 425, 426 neutral stability, 166, 339, 352 Newton’s Law, 46, 73, 239, 370 Newton’s method, 6, 181 nodal analysis, 123 node, 313, 423 nondiagonalizable, 339, 342, 346, 383 nonlinear equation, 1, 53, 172 nonlinear oscillation, 71 norm, 400, 401 normal distribution, 458 normal equations, 387, 389 normal modes, 373 Nth order equation, 107, 117 null solution, 17, 18, 78, 92, 103, 106, 113, 203 nullity, 267 nullspace, 261 number of solutions, 282 O ODE 45, 191, 193 off-diagonal ratios, 227 Ohm’s Law, 39, 122, 424, 425, 427 one-way wave, 463, 468 open-loop, 64 operation count, 452 optimal control, 478 order of accuracy, 186, 190, 192 orthogonal basis, 399, 433, 447, 448 Index orthogonal eigenvectors, 239, 375 orthogonal functions, 323, 405, 434 orthogonal matrix, 238, 242, 376, 381 orthogonal subspace, 306 orthonormal basis, 398, 400, 440 orthonormal columns, 242, 397 oscillation, 74, 75 oscillation equation, 372 overdamping, 96, 100, 102 overshoot (Gibbs), 435, 436 P PF2, 62, 142, 149, 472 PF3, 143, 149, 472 parabolas, 91, 96 parallel, 122, 127 partial differential equation, (see PDE) partial fractions, 56, 62, 142-149, 474 partial sums, 438 particular solution, 17, 18, 41, 106, 203, 274, 276, 278 PDE, 416, 455, 466 peak time, 113, 128 pendulum, 71, 81, 182 period, 76, 163, 444 periodic, 173 permutation matrix, 241, 246, 299, 450 perpendicular, 201, 243, 389, 433, 434 perpendicular eigenvectors, 383 perpendicular subspaces, 312 phase angle, 32, 80 phase lag, 30, 33, 75, 81, 112 phase line, 170 phase plane, 59, 351 phase response, 77 pictures, 153, 162 pivot, 210, 212, 225, 233, 402 pivot column, 262, 264, 290, 294 pivot variable, 264, 270 plane, 201, 207, 258 Pluto, 155 point source, 23, 457, 458 point-spread function, 484 Poisson’s equation, 417 polar angle, 38, 83 499 Index polar form, 30, 32, 84, 110, 112, 121, 244, 418, 431, 448 poles, 100, 129, 140, 471–473 polynomial, 131 Pontryagin, 478 population, 47, 55, 61, 63 positive definite, 372, 385, 396, 403-411 positive definite matrix, 372, 382, 396 positive semidefinite, 412, 413 potential energy, 79 powers, 221, 328, 341 practical resonance, 126 predator-prey, 172, 174, 180 prediction-correction, 191 present value, 51 principal axis, 376 Principal Component Analysis, 401, 431 probability, 458 product integral, 384 product of pivots, 330, 492 product rule, 8 projection, 387, 389–391, 394 projection matrix, 247, 334, 382, 389, 394 pulse, 392, 393 Python, 330 Q quadratic formula, 90 quiver, 155 R rabbits, 172, 174 radians, 76 radioactive decay, 45 ramp function, 23, 98, 407, 408, 477 ramp response, 129 rank, 267, 273, 277, 301 rank of AB, 311 rank one matrix, 305, 382, 401 rank theorem, 322 Rayleigh quotient, 431 reactance, 121 real eigenvalues, 166, 239, 375 real roots, 90, 162 real solution, 31, 111 rectangular form, 110, 111 rectangular matrix, 385 recursion, 452, 453 red lights, 478 reflection matrix, 247, 382 relativity, 464 relaxation time, 46 repeated eigenvalues, 338, 339, 355, 383 repeated roots, 90, 92, 101, 355 repeating ramp, 436 resistance, 119, 426 resonance, 26, 27, 29, 79, 82, 108, 109, 114, 116, 132, 137, 364 response, 77 reverse order, 229, 238, 248 right triangle, 129, 386 right-inverse, 228, 232, 233 RLC loop, 39, 118, 119, 122 roots, 101, 108, 129 roots of z N D 1, 448 rotation matrix, 331 row exchange, 212, 216, 242 row picture, 198, 199, 214 row space, 289, 323 rref .A/, 263, 265, 267, 268, 284 Runge-Kutta, 16, 191–193 S S -curve, 54, 64, 157 saddle, 162, 169, 173, 177, 402, 428 saddle-point matrix, 428, 430 SciPy, 194 second difference, 240, 246, 410, 414, 415 semidefinite, 398, 412 separable, 56, 65 separation of variables, 421, 422, 456, 459, 460, 466 shift, 441 shift invariance, 98, 459, 480, 482, 487 shift rule for transform, 475 sign reversal, 492 similar matrix, 365, 370, 383 Simpson’s Rule, 195 sines and cosines, 439 singular matrix, 202, 205, 218, 326, 492 500 singular value, 398, 400, 405 Singular Value Decomposition, (see SVD) singular vector, 385 sink, 17, 162 sinusoid, 19, 30, 34 sinusoidal identity, 35, 37, 112 SIR model, 179 six pictures, 162, 171 skew-symmetric, 381 smoothness, 437 solution curve, 154 Solution Page, 117 solvable, 255, 257, 277, 311 source, 17, 19, 40, 162 span, 256, 260, 285, 288, 296 sparse matrices, 223 special inputs, 131, 139 special solution, 261, 265, 302 spectral theorem, 376, 383 speed of light, 464 spike, 23, 407, 437, 438 spiral, 33, 86, 88, 95, 161 spiral sink, 163 spring, 74, 119 square root, 397 square wave, 435, 437, 443, 456 stability, 49, 58–60, 187, 188 stability limit, 190, 195 stability line, 58, 170 stability test, 165-170, 175, 188, 339, 353 stable, 161, 169, 352, 472 standing wave, 465 starting value (initial condition), 2, 9 state space, 127 statistics, 401, 458 steady state, 21, 49, 53, 58, 155, 328, 357 Stefan-Boltzmann Law, 49, 63 step function, 21, 23, 474, 475, 478, 489 step response, 22, 81, 97, 102, 124–128 stepsize, 184 stiff equation, 187 stiff system, 193 stiffness, 118, 468 stiffness matrix, 124, 372, 385 Index stock prices, 457 straight line, 386 subspace, 251–254, 256, 258, 296 Sudoku matrix, 209 sum of spaces, 260 sum of squares, 386, 388 superposition, 8, 349, 460 SVD, 244, 398, 382, 385, 399-405, 431 switch, 22 symmetric and orthogonal, 244, 378 symmetric matrix, 238, 239, 292, 375, 409 symmetry, 468 system, 164, 197, 325 T Table of Eigenvalues, 382 Table of Rules, 476 Table of Transforms, 146, 471 tangent, 75, 80, 156 tangent line, 6, 184 tangent parabola, 7, 191 Taylor series, 7, 10, 14, 16, 185 temperature, 46, 442, 455, 459 test grades, 395 three steps, 341, 349, 369 time constant, 100 time domain, 120, 127 time lag, 81 time-varying, 367, 371, 384 Toeplitz matrix, 480, 482 Toomre, 178 trace, 175, 331, 332, 336, 347, 353, 384 transfer function, 104, 121, 432, 477, 481 transient, 27, 103 tree, 317 triangular matrix, 213, 238, 293, 490, 492 tridiagonal matrix, 232, 246, 382, 410, 454 tumbling box, 176, 178, 183 U underdamping, 96, 100, 102, 117 undetermined coefficients, 117, 130-137 uniqueness, 154, 289 unit circle, 33, 84, 85, 94, 448 unit vector, 334 501 Index unitary matrix, 377 units, 44, 52, 456 unstable, 49, 53, 166 upper triangular, 210, 213 V variable coefficient, 1, 42, 130 variance, 392, 395, 401, 431 variation of parameters, 41, 43, 130, 133–135, 138, 482 vector, 164, 199, 200, 251, 252 vector space, 251, 252, 298, 321 very particular, 26, 27, 117, 144 violin, 465, 469 Voltage Law, 123, 317, 318 voltage source, 425 W wave equation, 463–466, 469 weighted Laplacian, 424 weighted least squares, 390, 392 Wikipedia, 243, 431 Wolfram Alpha, 194 Wronskian, 134, 135, 366, 384 Z zerocline, 157 zeta, 99, 113 Index of Symbols A D LU , 414, 490 A D QR, 490 A D QS , 431 A D U †V T , 382, 398, 401 A D VƒV 1 , 337, 341 AT A, 239, 276, 312, 385, 395, 417, 423 AT CA, 392, 404, 416, 425, 427 A D AN T , 413 K2D, 419, 420 K D AT CA, 410, 423, 424 P .D/, 108, 117 Q, 238 S D LDLT , 403 S D QƒQT , 376 S ? , 307 C .A/ and N .A/, 255, 261 Rn and Cn , 251