Spreadsheet: 69640d1270164576-interpolation-scratch
Sheet: Interpolation

Months | Added column | Factor |  | Month | Factor |  | x^6 | [NAME] | x^4 | x^3 | x^2 | x^1 | b
1 - 12 | 6 | 3.412 |  | 1 | 4.382531484430776 |  | 1.440827406208367e-11 | -7.095503131808914e-09 | 1.399101382958452e-06 | -0.0001422285569765799 | 0.007985370797128412 | -0.244752490341071 | 4.619439440511407 | << This is ONE array formula
13 - 24 | 18 | 2.093 |  | 2 | 4.160760274050122
25 - 36 | 30 | 1.616 |  | 3 | 3.953321749132372
37 - 48 | 42 | 1.386 |  | 4 | 3.759443747429797
49 - 60 | 54 | 1.275 |  | 5 | 3.578385179158534
61 - 72 | 66 | 1.221 |  | 6 | 3.409435211847058
73 - 84 | 78 | 1.171 |  | 7 | 3.251912465558616
85 - 96 | 90 | 1.139 |  | 8 | 3.105164218487618
97 - 108 | 102 | 1.122 |  | 9 | 2.968565622929978
109 - 120 | 114 | 1.095 |  | 10 | 2.841518931627424
121 - 132 | 126 | 1 |  | 11 | 2.723452734485754
 |  |  |  | 12 | 2.613821205667064
 |  |  |  | 13 | 2.512103361055914
 |  |  |  | 14 | 2.417802326099464
 |  |  |  | 15 | 2.33044461402157
 |  |  |  | 16 | 2.249579414410825
 |  |  |  | 17 | 2.17477789218257
 |  |  |  | 18 | 2.105632496914853
 |  |  |  | 19 | 2.041756282558352
 |  |  |  | 20 | 1.98278223752025
 |  |  |  | 21 | 1.928362625122066
 |  |  |  | 22 | 1.878168334431462
 |  |  |  | 23 | 1.831888241467972
 |  |  |  | 24 | 1.789228580782721
 |  |  |  | 25 | 1.74991232741209
 |  |  |  | 26 | 1.71367858920533
 |  |  |  | 27 | 1.680282009526147
 |  |  |  | 28 | 1.649492180328231
 |  |  |  | 29 | 1.621093065604759
 |  |  |  | 30 | 1.594882435211838
 |  |  |  | 31 | 1.570671309065917
 |  |  |  | 32 | 1.548283411715144
 |  |  |  | 33 | 1.527554637284704
 |  |  |  | 34 | 1.508332524796087
 |  |  |  | 35 | 1.490475743860322
 |  |  |  | 36 | 1.473853590745186
 |  |  |  | 37 | 1.458345494816346
 |  |  |  | 38 | 1.443840535352465
 |  |  |  | 39 | 1.430236968734278
 |  |  |  | 40 | 1.417441766007613
 |  |  |  | 41 | 1.405370160820362
 |  |  |  | 42 | 1.393945207733438
 |  |  |  | 43 | 1.383097350905656
 |  |  |  | 44 | 1.372764003152591
 |  |  |  | 45 | 1.36288913537939
 |  |  |  | 46 | 1.353422876387532
 |  |  |  | 47 | 1.344321123055567
 |  |  |  | 48 | 1.335545160893792
 |  |  |  | 49 | 1.32706129497288
 |  |  |  | 50 | 1.318840491226497
 |  |  |  | 51 | 1.310858028127841
 |  |  |  | 52 | 1.303093158740159
 |  |  |  | 53 | 1.295528783141215
 |  |  |  | 54 | 1.288151131221721
 |  |  |  | 55 | 1.28094945585771
 |  |  |  | 56 | 1.2739157364569
 |  |  |  | 57 | 1.267044392878956
 |  |  |  | 58 | 1.26033200972978
 |  |  |  | 59 | 1.253777071029706
 |  |  |  | 60 | 1.247379705255682
 |  |  |  | 61 | 1.241141440757371
 |  |  |  | 62 | 1.235064971547278
 |  |  |  | 63 | 1.229153933464744
 |  |  |  | 64 | 1.223412690714007
 |  |  |  | 65 | 1.217846132776096
 |  |  |  | 66 | 1.212459481694765
 |  |  |  | 67 | 1.207258109736415
 |  |  |  | 68 | 1.202247367423837
 |  |  |  | 69 | 1.197432421944033
 |  |  |  | 70 | 1.19281810593003
 |  |  |  | 71 | 1.188408776616459
 |  |  |  | 72 | 1.184208185369307
 |  |  |  | 73 | 1.180219357589479
 |  |  |  | 74 | 1.176444482990398
 |  |  |  | 75 | 1.172884816249528
 |  |  |  | 76 | 1.169540588033854
 |  |  |  | 77 | 1.166410926399358
 |  |  |  | 78 | 1.163493788564359
 |  |  |  | 79 | 1.160785903056968
 |  |  |  | 80 | 1.158282722236279
 |  |  |  | 81 | 1.155978385187755
 |  |  |  | 82 | 1.153865690992429
 |  |  |  | 83 | 1.151936082370018
 |  |  |  | 84 | 1.150179639696216
 |  |  |  | 85 | 1.148585085393659
 |  |  |  | 86 | 1.147139798697022
 |  |  |  | 87 | 1.145829840792121
 |  |  |  | 88 | 1.144639990328766
 |  |  |  | 89 | 1.14355378930777
 |  |  |  | 90 | 1.14255359934182
 |  |  |  | 91 | 1.141620668290319
 |  |  |  | 92 | 1.14073520726819
 |  |  |  | 93 | 1.139876478028693
 |  |  |  | 94 | 1.139022890719982
 |  |  |  | 95 | 1.138152112016027
 |  |  |  | 96 | 1.13724118362104
 |  |  |  | 97 | 1.136266651148144
 |  |  |  | 98 | 1.135204703371937
 |  |  |  | 99 | 1.134031321855002
 |  |  |  | 100 | 1.132722440948267
 |  |  |  | 101 | 1.131254118165625
 |  |  |  | 102 | 1.129602714932116
 |  |  |  | 103 | 1.127745087706312
 |  |  |  | 104 | 1.125658789476741
 |  |  |  | 105 | 1.123322281631953
 |  |  |  | 106 | 1.120715156204849
 |  |  |  | 107 | 1.11781836849077
 |  |  |  | 108 | 1.114614480039702
 |  |  |  | 109 | 1.111087912022267
 |  |  |  | 110 | 1.107225208969776
 |  |  |  | 111 | 1.103015312888385
 |  |  |  | 112 | 1.098449847746714
 |  |  |  | 113 | 1.093523414338073
 |  |  |  | 114 | 1.088233895516218
 |  |  |  | 115 | 1.082582771805058
 |  |  |  | 116 | 1.076575447382645
 |  |  |  | 117 | 1.070221586438784
 |  |  |  | 118 | 1.063535459906582
 |  |  |  | 119 | 1.056536302568638
 |  |  |  | 120 | 1.049248680535904
 |  |  |  | 121 | 1.041702869101762
 |  |  |  | 122 | 1.033935240969647
 |  |  |  | 123 | 1.025988664853749
 |  |  |  | 124 | 1.017912914455714
 |  |  |  | 125 | 1.009765087812688
 |  |  |  | 126 | 1.001610037021742
 |  |  |  | 127 | 0.9935208083366049
 |  |  |  | 128 | 0.9855790926389076
 |  |  |  | 129 | 0.9778756862839444
 |  |  |  | 130 | 0.9705109623191319
 |  |  |  | 131 | 0.9635953520777392
 |  |  |  | 132 | 0.957249837145774