Question: 2022年02月21日-2022年04月19日，白云山双指数移动平均线中20日均线和10日均线金叉的次数是多少？（平滑系数 alpha 取 2 / (n + 1)；从前 5n 个数据开始计算；初始值用首个数据点）使用不复权价格，写出指标公式，搜集原始数据，计算得出答案，保留四位小数。注意列出原始数据和关键计算过程。
Formula: DEMA = 2 * EMA1 - EMA2；EMA1 = EMA_n(P)；EMA2 = EMA_n(EMA1)
Data:
date,close
2021-09-15,30.64
2021-09-16,30.01
2021-09-17,30.28
2021-09-22,30.11
2021-09-23,30.7
2021-09-24,30.63
2021-09-27,30.93
2021-09-28,30.27
2021-09-29,29.73
2021-09-30,29.77
2021-10-08,30.35
2021-10-11,30.43
2021-10-12,30.1
2021-10-13,30.8
2021-10-14,30.12
2021-10-15,30.2
2021-10-18,29.95
2021-10-19,30.2
2021-10-20,30.02
2021-10-21,29.79
2021-10-22,29.8
2021-10-25,29.65
2021-10-26,30.22
2021-10-27,29.12
2021-10-28,29.02
2021-10-29,29.12
2021-11-01,29.23
2021-11-02,28.8
2021-11-03,28.86
2021-11-04,28.96
2021-11-05,29.11
2021-11-08,28.97
2021-11-09,29.12
2021-11-10,29.26
2021-11-11,29.27
2021-11-12,29.06
2021-11-15,29.23
2021-11-16,29.39
2021-11-17,29.51
2021-11-18,29.13
2021-11-19,29.23
2021-11-22,29.08
2021-11-23,29.12
2021-11-24,29.12
2021-11-25,29.8
2021-11-26,29.44
2021-11-29,29.48
2021-11-30,29.38
2021-12-01,29.39
2021-12-02,29.36
2021-12-03,29.42
2021-12-06,29.55
2021-12-07,29.99
2021-12-08,30.02
2021-12-09,30.3
2021-12-10,29.94
2021-12-13,29.9
2021-12-14,29.91
2021-12-15,29.63
2021-12-16,29.79
2021-12-17,29.92
2021-12-20,30.78
2021-12-21,30.64
2021-12-22,31.55
2021-12-23,31.72
2021-12-24,32.71
2021-12-27,33.17
2021-12-28,32.59
2021-12-29,32.17
2021-12-30,32.28
2021-12-31,34.2
2022-01-04,34.49
2022-01-05,34.01
2022-01-06,35.29
2022-01-07,33.78
2022-01-10,34.13
2022-01-11,35.03
2022-01-12,34.01
2022-01-13,32.72
2022-01-14,32.99
2022-01-17,33.0
2022-01-18,32.95
2022-01-19,32.34
2022-01-20,32.28
2022-01-21,31.34
2022-01-24,30.99
2022-01-25,29.9
2022-01-26,29.82
2022-01-27,29.24
2022-01-28,29.1
2022-02-07,29.39
2022-02-08,29.71
2022-02-09,30.27
2022-02-10,30.3
2022-02-11,29.58
2022-02-14,29.5
2022-02-15,29.87
2022-02-16,29.87
2022-02-17,29.6
2022-02-18,29.74
2022-02-21,30.07
2022-02-22,29.85
2022-02-23,29.99
2022-02-24,29.61
2022-02-25,29.77
2022-02-28,29.79
2022-03-01,29.72
2022-03-02,29.98
2022-03-03,30.27
2022-03-04,30.36
2022-03-07,29.98
2022-03-08,28.5
2022-03-09,27.61
2022-03-10,28.83
2022-03-11,29.44
2022-03-14,29.03
2022-03-15,27.35
2022-03-16,28.12
2022-03-17,29.04
2022-03-18,29.95
2022-03-21,30.2
2022-03-22,30.12
2022-03-23,30.45
2022-03-24,30.59
2022-03-25,30.43
2022-03-28,30.46
2022-03-29,31.02
2022-03-30,31.27
2022-03-31,31.36
2022-04-01,31.04
2022-04-06,31.45
2022-04-07,30.7
2022-04-08,30.2
2022-04-11,30.01
2022-04-12,30.2
2022-04-13,29.58
2022-04-14,29.78
2022-04-15,29.65
2022-04-18,29.11
2022-04-19,29.4

Indicator data:
date,20日,10日
2021-11-17,29.112162707704158,29.270594186148102
2021-11-18,29.092451473743168,29.223790349591933
2021-11-19,29.0947971396051,29.222416199514107
2021-11-22,29.070732733296104,29.172160241213604
2021-11-23,29.0583740448364,29.148694343798763
2021-11-24,29.04881626090602,29.132037194494664
2021-11-25,29.1649939818981,29.34528200547308
2021-11-26,29.200549948679384,29.384056399418196
2021-11-29,29.239083971838863,29.42508532761557
2021-11-30,29.25467228583708,29.421308483595116
2021-12-01,29.270383606041186,29.42072039847084
2021-12-02,29.27888757921469,29.40939381591754
2021-12-03,29.297468948826424,29.42001341550029
2021-12-06,29.337373707634885,29.470097166774682
2021-12-07,29.451786685184356,29.651720267486475
2021-12-08,29.55576840435583,29.794402830194812
2021-12-09,29.69589159483991,29.98993734472867
2021-12-10,29.750768931314724,30.012074090995842
2021-12-13,29.790151341160872,30.01128714953846
2021-12-14,29.82519996834866,30.010387225107042
2021-12-15,29.803866078419855,29.913904226930406
2021-12-16,29.813850208628523,29.892823733045873
2021-12-17,29.84538959677096,29.918288072410906
2021-12-20,30.027893362603923,30.219688561658213
2021-12-21,30.15871487284265,30.39369422597556
2021-12-22,30.43524935289891,30.819146142552444
2021-12-23,30.70256896715904,31.184311602655892
2021-12-24,31.110215463483915,31.77374264280264
2021-12-27,31.541869711373586,32.351337218675994
2021-12-28,31.804771535960153,32.57331913413911
2021-12-29,31.95091319703025,32.58362705658502
2021-12-30,32.09248572958849,32.61321741602122
2021-12-31,32.558376299509504,33.256721130486085
2022-01-04,33.0072492939391,33.81454688544234
2022-01-05,33.30106823682645,34.0516187747786
2022-01-06,33.78021645776758,34.63208446020937
2022-01-07,33.912215645814456,34.54323638317677
2022-01-10,34.08256223153251,34.574231095802
2022-01-11,34.385702522956755,34.87781495811137
2022-01-12,34.45466133273526,34.74888134666191
2022-01-13,34.27306379305068,34.21169830604989
2022-01-14,34.15930196312249,33.892040293539374
2022-01-17,34.05738534530714,33.651540622568206
2022-01-18,33.955295911265026,33.452477516461286
2022-01-19,33.751950175813185,33.10095667629183
2022-01-20,33.56180139757879,32.820650769193534
2022-01-21,33.22399887029323,32.3043914175263
2022-01-24,32.866895224417355,31.81121312698785
2022-01-25,32.35981586600724,31.093590862181536
2022-01-26,31.907899966120446,30.547295267982868
2022-01-27,31.413810987155323,29.96581490267689
2022-01-28,30.964238730114445,29.506284578705888
2022-02-07,30.63192004595976,29.281101979065596
2022-02-08,30.406671236064795,29.2397449667753
2022-02-09,30.317552176390556,29.4127292819603
2022-02-10,30.24961070417295,29.566785582804464
2022-02-11,30.063839016446764,29.456136145095037
2022-02-14,29.89286637396391,29.359713425798805
2022-02-15,29.816465944412503,29.422117607896414
2022-02-16,29.754410572880285,29.47869833779989
2022-02-17,29.65568124994457,29.440254087973294
2022-02-18,29.59975378831289,29.466080529396038
2022-02-21,29.615107918012917,29.601515402434536
2022-02-22,29.591893426288784,29.63493823802446
2022-02-23,29.60062810833512,29.71070267381525
2022-02-24,29.542375745036676,29.645034149879653
2022-02-25,29.524329019116298,29.652808637166416
2022-02-28,29.51541250180628,29.668498710898337
2022-03-01,29.4979056701597,29.659878059069342
2022-03-02,29.532754674910144,29.742045124900535
2022-03-03,29.617946221430024,29.900783569799085
2022-03-04,29.709924369747384,30.04900406366343
2022-03-07,29.72217927692104,30.032887069848215
2022-03-08,29.466068856018552,29.531093476638087
2022-03-09,29.08620459894402,28.8668814522036
2022-03-10,28.9831755395343,28.78399963577378
2022-03-11,29.008104808003583,28.931690332683615
2022-03-14,28.95805275967115,28.911824093997346
2022-03-15,28.612971125914477,28.347059947637206
2022-03-16,28.45871635428224,28.19057948775523
2022-03-17,28.49626547451724,28.387627130718357
2022-03-18,28.697014160473625,28.841927548545957
2022-03-21,28.91806227609349,29.265321132429033
2022-03-22,29.096126041704366,29.553202089163026
2022-03-23,29.311038774626603,29.873743817582866
2022-03-24,29.522692610196728,30.153652121150436
2022-03-25,29.676607041489305,30.302560915401443
2022-03-28,29.814876160606456,30.41637387963884
2022-03-29,30.035501211306833,30.6791288762064
2022-03-30,30.270384745224312,30.948935811885292
2022-03-31,30.488052356932503,31.169916130417928
2022-04-01,30.61609271611374,31.218343744297865
2022-04-06,30.79912718051277,31.38040375873657
2022-04-07,30.818807300526373,31.243257032576146
2022-04-08,30.743136765657454,30.968199900763757
2022-04-11,30.64179978118963,30.69586579101286
2022-04-12,30.587582433077063,30.553696154203987
2022-04-13,30.427213289310746,30.241873631903694
2022-04-14,30.324532758569514,30.077368517573625
2022-04-15,30.211957242397485,29.91443968839156
2022-04-18,30.01674728705125,29.61811742461211
2022-04-19,29.90133281306441,29.498823432342824

Answer: 2.0