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Talk:Defective matrix

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For a matrix to have eigenvectors, it must represent a linear transformation of a finite-dimensional vector space into itself and hence must be a square matrix. Note also from the lead that a defective matrix "is therefore not diagonalizable." This is a result—not the definition. The inference
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Does a defective matrix truly need to be square? In other words, non-diagonalizable matrices can be found which are not square (all of these, in fact), and also not diagonalizable, which seems to be the word sense of "defective". Since failing diagonalization is a trait not limited to square
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does not hold in the other direction, that is, a matrix which is not diagonalizable is not necessarily a defective matrix. For more information about eigenvectors, see most any linear algebra textbook. For more information about defective matrices, see Golub and Van Loan.—
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matrices, it seems artificial to limit these matrices to being square. Are there different conventions on this, or is there some other terminology which helps clarify the status of these non-square matrices with respect to the definition of defective matrix?
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A matrix is singular iff one of its eigenvalues is zero. Whether a matrix is defective has to do with the multiplicities of the eigenvalues, and not with the location of the eigenvalues. This explains why the properties are independent. --
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I didn't revert your example entirely. I just changed it to something a bit more simple. I agree that the singular one wasn't so good. This article actually needs a bit of help. There is no mention of the connection to the
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Hi Plastikspork. I see you reverted my change to the simple example. Could you explain your reasoning? You said "It was already a simple example". My objection to the original example was that it was
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Perhaps I'm overlooking something simple, but isn't a matrix singular iff its determinate is zero? The same appears from the examples to be true of a defective matrix.
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Not. All four combinations (invertible + diagonalizable, invertible + defective, singular + diagonalizable, singlar + defective) are possible. --
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Sorry, I didn't look very carefully at what you'd done - too hasty with my indignation. --
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It's dangerous to generalize from one example :) Here are some others:
377:{\displaystyle {\begin{bmatrix}0&0\\0&1\end{bmatrix}}} 322:{\displaystyle {\begin{bmatrix}1&1\\0&1\end{bmatrix}}} 196: 158: 15: 343: 288: 425:
I think this page should be merged with its antonym,
337: 282: 101:, a collaborative effort to improve the coverage of 376: 321: 204:This page has archives. Sections older than 8: 19: 518: 47: 338: 336: 283: 281: 476:and the defective property of a general 456:), which I thought might be confusing.-- 225:How does this relate to a matrix being 49: 214:when more than 5 sections are present. 7: 95:This article is within the scope of 38:It is of interest to the following 14: 570:Mid-priority mathematics articles 208:may be automatically archived by 115:Knowledge:WikiProject Mathematics 565:Start-Class mathematics articles 163: 118:Template:WikiProject Mathematics 82: 72: 51: 20: 135:This article has been rated as 1: 384:is singular and not defective 234:22:22, 21 December 2006 (UTC) 109:and see a list of open tasks. 550:07:41, 11 January 2017 (UTC) 533:06:07, 11 January 2017 (UTC) 439:14:48, 5 January 2007 (UTC) 409:16:16, 5 January 2007 (UTC) 400:15:48, 5 January 2007 (UTC) 329:is invertible and defective 262:14:53, 5 January 2007 (UTC) 249:14:48, 5 January 2007 (UTC) 586: 504:09:07, 21 April 2010 (UTC) 490:01:58, 21 April 2010 (UTC) 466:00:18, 21 April 2010 (UTC) 480:. Thanks for your help. 134: 67: 46: 141:project's priority scale 98:WikiProject Mathematics 378: 323: 211:Lowercase sigmabot III 28:This article is rated 474:Jordan canonical form 427:diagonalizable matrix 379: 324: 335: 280: 121:mathematics articles 374: 368: 319: 313: 90:Mathematics portal 34:content assessment 535: 523:comment added by 218: 217: 178:no archives yet ( 155: 154: 151: 150: 147: 146: 577: 444:Singular example 383: 381: 380: 375: 373: 372: 328: 326: 325: 320: 318: 317: 221:Singular matrix? 213: 197: 167: 159: 123: 122: 119: 116: 113: 92: 87: 86: 76: 69: 68: 63: 55: 48: 31: 25: 24: 16: 585: 584: 580: 579: 578: 576: 575: 574: 555: 554: 514: 487: 446: 423: 406:—Ben FrantzDale 367: 366: 361: 355: 354: 349: 339: 333: 332: 312: 311: 306: 300: 299: 294: 284: 278: 277: 259:—Ben FrantzDale 231:—Ben FrantzDale 223: 209: 198: 192: 172: 120: 117: 114: 111: 110: 88: 81: 61: 32:on Knowledge's 29: 12: 11: 5: 583: 581: 573: 572: 567: 557: 556: 553: 552: 525:75.139.254.117 513: 512:Square matrix? 510: 509: 508: 507: 506: 485: 445: 442: 422: 419: 418: 417: 416: 415: 414: 413: 412: 411: 387: 386: 385: 371: 365: 362: 360: 357: 356: 353: 350: 348: 345: 344: 342: 330: 316: 310: 307: 305: 302: 301: 298: 295: 293: 290: 289: 287: 267: 266: 265: 264: 252: 251: 222: 219: 216: 215: 203: 200: 199: 194: 190: 188: 185: 184: 174: 173: 168: 162: 153: 152: 149: 148: 145: 144: 133: 127: 126: 124: 107:the discussion 94: 93: 77: 65: 64: 56: 44: 43: 37: 26: 13: 10: 9: 6: 4: 3: 2: 582: 571: 568: 566: 563: 562: 560: 551: 547: 543: 538: 537: 536: 534: 530: 526: 522: 511: 505: 501: 497: 493: 492: 491: 488: 483: 479: 475: 470: 469: 468: 467: 463: 459: 455: 451: 443: 441: 440: 436: 432: 428: 420: 410: 407: 404:Aah. thanks. 403: 402: 401: 397: 393: 388: 369: 363: 358: 351: 346: 340: 331: 314: 308: 303: 296: 291: 285: 276: 275: 273: 272: 271: 270: 269: 268: 263: 260: 256: 255: 254: 253: 250: 246: 242: 238: 237: 236: 235: 232: 228: 220: 212: 207: 202: 201: 187: 186: 183: 181: 176: 175: 171: 166: 161: 160: 157: 142: 138: 132: 129: 128: 125: 108: 104: 100: 99: 91: 85: 80: 78: 75: 71: 70: 66: 60: 57: 54: 50: 45: 41: 35: 27: 23: 18: 17: 519:— Preceding 515: 482:Plastikspork 478:Jordan block 453: 449: 447: 431:Jitse Niesen 424: 392:Jitse Niesen 241:Jitse Niesen 224: 205: 177: 169: 156: 137:Mid-priority 136: 96: 62:Mid‑priority 40:WikiProjects 112:Mathematics 103:mathematics 59:Mathematics 30:Start-class 559:Categories 542:Anita5192 521:unsigned 496:catslash 458:catslash 450:singular 227:singular 206:365 days 170:Archives 139:on the 454:simple 180:create 36:scale. 452:(not 429:. -- 421:Merge 546:talk 529:talk 500:talk 462:talk 435:talk 396:talk 245:talk 131:Mid 561:: 548:) 531:) 502:) 486:―Œ 464:) 437:) 398:) 247:) 229:? 182:) 544:( 527:( 498:( 460:( 433:( 394:( 370:] 364:1 359:0 352:0 347:0 341:[ 315:] 309:1 304:0 297:1 292:1 286:[ 243:( 143:. 42::

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create
Lowercase sigmabot III
singular
—Ben FrantzDale
22:22, 21 December 2006 (UTC)
Jitse Niesen
talk
14:48, 5 January 2007 (UTC)
—Ben FrantzDale
14:53, 5 January 2007 (UTC)
Jitse Niesen
talk
15:48, 5 January 2007 (UTC)
—Ben FrantzDale
16:16, 5 January 2007 (UTC)
diagonalizable matrix

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