Knowledge (XXG)

Hat notation

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1075: 1386: 745: 32: 1070:{\displaystyle \mathbf {a} \times \mathbf {b} ={\begin{bmatrix}a_{x}\\a_{y}\\a_{z}\end{bmatrix}}\times {\begin{bmatrix}b_{x}\\b_{y}\\b_{z}\end{bmatrix}}={\begin{bmatrix}0&-a_{z}&a_{y}\\a_{z}&0&-a_{x}\\-a_{y}&a_{x}&0\end{bmatrix}}{\begin{bmatrix}b_{x}\\b_{y}\\b_{z}\end{bmatrix}}=\mathbf {\hat {a}} \mathbf {b} } 734: 427: 283: 649: 499: 1273: 1124: 180: 575: 539: 200: 1230: 1185: 337: 310: 1156: 42: 689: 342: 1427: 1364: 1095:
is a vector (often a spatial vector) of length 1. A unit vector is often denoted by a lowercase letter with a circumflex, or "hat", as in
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are denoted with hat notation. For instance, see the time-independent Schrödinger equation, where the
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indicates an observable estimate (the residuals) of an unobservable quantity called
660: 1385: 1086: 31: 729:{\displaystyle \mathbf {a} \times \mathbf {b} =\mathbf {\hat {a}} \mathbf {b} } 1304: 664: 586: 142: 138: 122: 146: 422:{\displaystyle {\hat {y}}_{i}={\hat {\beta }}_{0}+{\hat {\beta }}_{1}x_{i}} 1329: 1393: 1126:(pronounced "v-hat"). This is especially common in physics context. 205:
Another example of the hat operator denoting an estimator occurs in
49: 278:{\displaystyle y_{i}=\beta _{0}+\beta _{1}x_{i}+\varepsilon _{i}} 25: 1356:
Applied Mathematics for Physical Chemistry: Third Edition
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or an estimated value. For example, in the context of
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Pages displaying wikidata descriptions as a fallback
644:{\displaystyle {\hat {\mathbf {y} }}=H\mathbf {y} .} 494:{\displaystyle \sum _{i}(y_{i}-{\hat {y}}_{i})^{2}} 21:
Help:Displaying a formula § Special characters
1267: 1224: 1179: 1150: 1118: 1069: 728: 643: 569: 533: 493: 421: 331: 304: 277: 194: 174: 1056: 715: 285:, with observations of independent variable data 1292: – Meanings of symbols used in mathematics 683:and transforms it into its equivalent matrix. 1421: 599:of response variable to the predicted values 8: 58:introducing citations to additional sources 1286: – Algebra of exterior/ wedge products 1428: 1414: 145:(ˆ), called a "hat", is used to denote an 1307: – Diacritic (^) in European scripts 1242: 1241: 1239: 1211: 1210: 1208: 1166: 1165: 1163: 1143: 1105: 1103: 1102: 1100: 1062: 1051: 1050: 1033: 1019: 1005: 993: 974: 962: 945: 925: 911: 899: 879: 862: 848: 834: 822: 805: 791: 777: 765: 757: 749: 747: 721: 710: 709: 701: 693: 691: 671:operation. Since the cross product is a 633: 616: 614: 613: 611: 561: 550: 549: 546: 525: 514: 513: 510: 485: 475: 464: 463: 453: 440: 434: 413: 403: 392: 391: 381: 370: 369: 359: 348: 347: 344: 323: 317: 296: 290: 269: 256: 246: 233: 220: 214: 187: 161: 160: 158: 1359:. Waveland Press. Page 124, Footnote 1. 48:Relevant discussion may be found on the 1317: 1268:{\displaystyle {\hat {H}}\psi =E\psi } 1119:{\displaystyle {\hat {\mathbf {v} }}} 339:, the estimated model is of the form 175:{\displaystyle {\hat {\varepsilon }}} 19:For Knowledge (XXG) math syntax, see 7: 1382: 1380: 1323: 1321: 1091:In mathematics, a unit vector in a 570:{\displaystyle {\hat {\beta }}_{1}} 534:{\displaystyle {\hat {\beta }}_{0}} 1400:. You can help Knowledge (XXG) by 1298: – signal filtering technique 739:For example, in three dimensions, 14: 1353:Barrante, James R. (2016-02-10). 1384: 1290:Glossary of mathematical symbols 1106: 1063: 1053: 758: 750: 722: 712: 702: 694: 634: 617: 125:(ˆ)), placed over a symbol is a 41:relies largely or entirely on a 30: 1247: 1216: 1171: 1110: 621: 591:In statistics, the hat matrix 555: 519: 482: 469: 446: 397: 375: 353: 166: 1: 675:, it can be represented as a 667:operator is to represent the 595:projects the observed values 505:by finding optimal values of 1158:is traditionally denoted by 679:. The hat operator takes a 312:and dependent variable data 195:{\displaystyle \varepsilon } 153:, the "hat" over the letter 1468: 1379: 1225:{\displaystyle {\hat {H}}} 1180:{\displaystyle {\hat {f}}} 1084: 584: 501:is commonly minimized via 202:(the statistical errors). 18: 207:simple linear regression 577:for the observed data. 1396:-related article is a 1269: 1226: 1195:In quantum mechanics, 1181: 1152: 1120: 1071: 730: 645: 571: 535: 495: 423: 333: 306: 279: 209:. Assuming a model of 196: 176: 1447:Mathematical notation 1334:mathworld.wolfram.com 1270: 1227: 1182: 1153: 1121: 1072: 731: 673:linear transformation 646: 572: 536: 496: 424: 334: 332:{\displaystyle y_{i}} 307: 305:{\displaystyle x_{i}} 280: 197: 177: 127:mathematical notation 16:Mathematical notation 1238: 1207: 1201:Hamiltonian operator 1162: 1142: 1099: 746: 690: 610: 545: 509: 433: 343: 316: 289: 213: 186: 157: 151:errors and residuals 54:improve this article 1328:Weisstein, Eric W. 1093:normed vector space 129:with various uses. 1265: 1222: 1177: 1148: 1116: 1067: 1041: 987: 870: 813: 726: 641: 567: 531: 491: 445: 419: 329: 302: 275: 192: 172: 1409: 1408: 1366:978-1-4786-3300-6 1250: 1219: 1174: 1151:{\displaystyle f} 1136:Fourier transform 1130:Fourier transform 1113: 1059: 718: 663:, one use of the 624: 558: 522: 472: 436: 400: 378: 356: 169: 119: 118: 104: 1459: 1430: 1423: 1416: 1388: 1381: 1371: 1370: 1350: 1344: 1343: 1341: 1340: 1325: 1301: 1284:Exterior algebra 1274: 1272: 1271: 1266: 1252: 1251: 1243: 1231: 1229: 1228: 1223: 1221: 1220: 1212: 1186: 1184: 1183: 1178: 1176: 1175: 1167: 1157: 1155: 1154: 1149: 1125: 1123: 1122: 1117: 1115: 1114: 1109: 1104: 1076: 1074: 1073: 1068: 1066: 1061: 1060: 1052: 1046: 1045: 1038: 1037: 1024: 1023: 1010: 1009: 992: 991: 979: 978: 967: 966: 950: 949: 930: 929: 916: 915: 904: 903: 875: 874: 867: 866: 853: 852: 839: 838: 818: 817: 810: 809: 796: 795: 782: 781: 761: 753: 735: 733: 732: 727: 725: 720: 719: 711: 705: 697: 650: 648: 647: 642: 637: 626: 625: 620: 615: 576: 574: 573: 568: 566: 565: 560: 559: 551: 540: 538: 537: 532: 530: 529: 524: 523: 515: 500: 498: 497: 492: 490: 489: 480: 479: 474: 473: 465: 458: 457: 444: 428: 426: 425: 420: 418: 417: 408: 407: 402: 401: 393: 386: 385: 380: 379: 371: 364: 363: 358: 357: 349: 338: 336: 335: 330: 328: 327: 311: 309: 308: 303: 301: 300: 284: 282: 281: 276: 274: 273: 261: 260: 251: 250: 238: 237: 225: 224: 201: 199: 198: 193: 181: 179: 178: 173: 171: 170: 162: 114: 111: 105: 103: 62: 34: 26: 1467: 1466: 1462: 1461: 1460: 1458: 1457: 1456: 1437: 1436: 1435: 1434: 1377: 1375: 1374: 1367: 1352: 1351: 1347: 1338: 1336: 1327: 1326: 1319: 1314: 1299: 1280: 1236: 1235: 1205: 1204: 1193: 1160: 1159: 1140: 1139: 1132: 1097: 1096: 1089: 1083: 1040: 1039: 1029: 1026: 1025: 1015: 1012: 1011: 1001: 994: 986: 985: 980: 970: 968: 958: 952: 951: 941: 936: 931: 921: 918: 917: 907: 905: 895: 890: 880: 869: 868: 858: 855: 854: 844: 841: 840: 830: 823: 812: 811: 801: 798: 797: 787: 784: 783: 773: 766: 744: 743: 688: 687: 657: 608: 607: 589: 583: 548: 543: 542: 512: 507: 506: 481: 462: 449: 431: 430: 409: 390: 368: 346: 341: 340: 319: 314: 313: 292: 287: 286: 265: 252: 242: 229: 216: 211: 210: 184: 183: 155: 154: 135: 133:Estimated value 115: 109: 106: 63: 61: 47: 35: 24: 17: 12: 11: 5: 1465: 1463: 1455: 1454: 1449: 1439: 1438: 1433: 1432: 1425: 1418: 1410: 1407: 1406: 1389: 1373: 1372: 1365: 1345: 1316: 1315: 1313: 1310: 1309: 1308: 1302: 1296:Top-hat filter 1293: 1287: 1279: 1276: 1264: 1261: 1258: 1255: 1249: 1246: 1218: 1215: 1192: 1189: 1173: 1170: 1147: 1138:of a function 1131: 1128: 1112: 1108: 1085:Main article: 1082: 1079: 1078: 1077: 1065: 1058: 1055: 1049: 1044: 1036: 1032: 1028: 1027: 1022: 1018: 1014: 1013: 1008: 1004: 1000: 999: 997: 990: 984: 981: 977: 973: 969: 965: 961: 957: 954: 953: 948: 944: 940: 937: 935: 932: 928: 924: 920: 919: 914: 910: 906: 902: 898: 894: 891: 889: 886: 885: 883: 878: 873: 865: 861: 857: 856: 851: 847: 843: 842: 837: 833: 829: 828: 826: 821: 816: 808: 804: 800: 799: 794: 790: 786: 785: 780: 776: 772: 771: 769: 764: 760: 756: 752: 737: 736: 724: 717: 714: 708: 704: 700: 696: 656: 653: 652: 651: 640: 636: 632: 629: 623: 619: 585:Main article: 582: 579: 564: 557: 554: 528: 521: 518: 488: 484: 478: 471: 468: 461: 456: 452: 448: 443: 439: 416: 412: 406: 399: 396: 389: 384: 377: 374: 367: 362: 355: 352: 326: 322: 299: 295: 272: 268: 264: 259: 255: 249: 245: 241: 236: 232: 228: 223: 219: 191: 168: 165: 134: 131: 117: 116: 69:"Hat notation" 52:. Please help 38: 36: 29: 15: 13: 10: 9: 6: 4: 3: 2: 1464: 1453: 1452:Algebra stubs 1450: 1448: 1445: 1444: 1442: 1431: 1426: 1424: 1419: 1417: 1412: 1411: 1405: 1403: 1399: 1395: 1390: 1387: 1383: 1378: 1368: 1362: 1358: 1357: 1349: 1346: 1335: 1331: 1324: 1322: 1318: 1311: 1306: 1303: 1297: 1294: 1291: 1288: 1285: 1282: 1281: 1277: 1275: 1262: 1259: 1256: 1253: 1244: 1233: 1213: 1202: 1198: 1190: 1188: 1168: 1145: 1137: 1129: 1127: 1094: 1088: 1080: 1047: 1042: 1034: 1030: 1020: 1016: 1006: 1002: 995: 988: 982: 975: 971: 963: 959: 955: 946: 942: 938: 933: 926: 922: 912: 908: 900: 896: 892: 887: 881: 876: 871: 863: 859: 849: 845: 835: 831: 824: 819: 814: 806: 802: 792: 788: 778: 774: 767: 762: 754: 742: 741: 740: 706: 698: 686: 685: 684: 682: 678: 674: 670: 669:cross product 666: 662: 655:Cross product 654: 638: 630: 627: 606: 605: 604: 602: 598: 594: 588: 580: 578: 562: 552: 526: 516: 504: 503:least squares 486: 476: 466: 459: 454: 450: 441: 437: 414: 410: 404: 394: 387: 382: 372: 365: 360: 350: 324: 320: 297: 293: 270: 266: 262: 257: 253: 247: 243: 239: 234: 230: 226: 221: 217: 208: 203: 189: 163: 152: 148: 144: 140: 132: 130: 128: 124: 113: 102: 99: 95: 92: 88: 85: 81: 78: 74: 71: –  70: 66: 65:Find sources: 59: 55: 51: 45: 44: 43:single source 39:This article 37: 33: 28: 27: 22: 1402:expanding it 1391: 1376: 1355: 1348: 1337:. Retrieved 1333: 1234: 1194: 1133: 1090: 738: 661:screw theory 658: 600: 596: 592: 590: 204: 136: 120: 107: 97: 90: 83: 76: 64: 40: 1203:is denoted 1087:Unit vector 1081:Unit vector 1441:Categories 1339:2024-08-29 1312:References 1305:Circumflex 587:hat matrix 581:Hat matrix 143:circumflex 139:statistics 123:circumflex 80:newspapers 1263:ψ 1254:ψ 1248:^ 1217:^ 1197:operators 1172:^ 1111:^ 1057:^ 956:− 939:− 893:− 820:× 755:× 716:^ 699:× 622:^ 556:^ 553:β 520:^ 517:β 470:^ 460:− 438:∑ 398:^ 395:β 376:^ 373:β 354:^ 267:ε 244:β 231:β 190:ε 167:^ 164:ε 147:estimator 121:A "hat" ( 50:talk page 1278:See also 1191:Operator 110:May 2024 1394:algebra 94:scholar 1363:  681:vector 677:matrix 429:where 96:  89:  82:  75:  67:  1392:This 1330:"Hat" 101:JSTOR 87:books 1398:stub 1361:ISBN 1134:The 541:and 141:, a 73:news 665:hat 659:In 603:: 137:In 56:by 1443:: 1332:. 1320:^ 1232:. 1187:. 1429:e 1422:t 1415:v 1404:. 1369:. 1342:. 1260:E 1257:= 1245:H 1214:H 1169:f 1146:f 1107:v 1064:b 1054:a 1048:= 1043:] 1035:z 1031:b 1021:y 1017:b 1007:x 1003:b 996:[ 989:] 983:0 976:x 972:a 964:y 960:a 947:x 943:a 934:0 927:z 923:a 913:y 909:a 901:z 897:a 888:0 882:[ 877:= 872:] 864:z 860:b 850:y 846:b 836:x 832:b 825:[ 815:] 807:z 803:a 793:y 789:a 779:x 775:a 768:[ 763:= 759:b 751:a 723:b 713:a 707:= 703:b 695:a 639:. 635:y 631:H 628:= 618:y 601:ŷ 597:y 593:H 563:1 527:0 487:2 483:) 477:i 467:y 455:i 451:y 447:( 442:i 415:i 411:x 405:1 388:+ 383:0 366:= 361:i 351:y 325:i 321:y 298:i 294:x 271:i 263:+ 258:i 254:x 248:1 240:+ 235:0 227:= 222:i 218:y 112:) 108:( 98:· 91:· 84:· 77:· 60:. 46:. 23:.

Index

Help:Displaying a formula § Special characters

single source
talk page
improve this article
introducing citations to additional sources
"Hat notation"
news
newspapers
books
scholar
JSTOR
circumflex
mathematical notation
statistics
circumflex
estimator
errors and residuals
simple linear regression
least squares
hat matrix
screw theory
hat
cross product
linear transformation
matrix
vector
Unit vector
normed vector space
Fourier transform

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