text: Title: ATR/RMA differences with TradingView
  Body: Let's take weekly BINANCE:BTCUSDT indicator since beginning (14.08.2017) and do ATR with period=7 and RMA with period=7.
  
  Python results:
  ```python
  import pandas as pd
  import numpy as np
  import pandas_ta as ta
  
  df = pd.DataFrame({'datetime': {0: '2017-08-14 00:00:00', 1: '2017-08-21 00:00:00', 2: '2017-08-28 00:00:00', 3: '2017-09-04 00:00:00', 4: '2017-09-11 00:00:00', 5: '2017-09-18 00:00:00', 6: '2017-09-25 00:00:00', 7: '2017-10-02 00:00:00', 8: '2017-10-09 00:00:00', 9: '2017-10-16 00:00:00', 10: '2017-10-23 00:00:00', 11: '2017-10-30 00:00:00', 12: '2017-11-06 00:00:00', 13: '2017-11-13 00:00:00'}, 'open': {0: 4261.48, 1: 4069.13, 2: 4310.01, 3: 4505.0, 4: 4153.62, 5: 3690.0, 6: 3660.02, 7: 4400.0, 8: 4640.0, 9: 5710.0, 10: 5975.0, 11: 6133.01, 12: 7345.1, 13: 5839.94}, 'high': {0: 4485.39, 1: 4453.91, 2: 4939.19, 3: 4788.59, 4: 4394.59, 5: 4123.2, 6: 4406.52, 7: 4658.0, 8: 5922.3, 9: 6171.0, 10: 6189.88, 11: 7590.25, 12: 7770.02, 13: 8123.15}, 'low': {0: 3850.0, 1: 3400.0, 2: 4124.54, 3: 3603.0, 4: 2817.0, 5: 3505.55, 6: 3653.69, 7: 4110.0, 8: 4550.0, 9: 5037.95, 10: 5286.98, 11: 6030.0, 12: 5325.01, 13: 5699.99}, 'close': {0: 4086.29, 1: 4310.01, 2: 4509.08, 3: 4130.37, 4: 3699.99, 5: 3660.02, 6: 4378.48, 7: 4640.0, 8: 5709.99, 9: 5950.02, 10: 6169.98, 11: 7345.01, 12: 5811.03, 13: 8038.0}})
  atr = df.ta.atr(length=7)
  rma = df.ta.rma(length=7)
  
  print(atr)
  0      635.390000
  1      860.746923
  2      842.961496
  3      949.315864
  4     1116.350102
  5      998.287017
  6      945.164499
  7      865.099081
  8      961.674618
  9      992.824763
  10     977.091686
  11    1075.946678
  12    1301.999156
  13    1483.088680
  Name: ATR_7, dtype: float64
  
  print(rma)
  0     4086.290000
  1     4206.754615
  2     4323.399843
  3     4263.481982
  4     4113.670859
  5     4006.272806
  6     4086.826964
  7     4198.342546
  8     4486.173579
  9     4752.250467
  10    5000.293910
  11    5397.762117
  12    5465.998719
  13    5881.427506
  Name: RMA_7, dtype: float64
  ```
  
  Now compare to TradingView built-in ATR (its using RMA)
  Here is pine script
  ```
  //@version=4
  study("My Script")
  plot(atr(7), title="ATR")
  plot(rma(close, 7), title="RMA")
  ```
  **TradingView results are:
  ATR:**
  NaN
  NaN
  NaN
  NaN
  NaN
  NaN
  NaN
  948.2300000000000
  891.0542857142860
  959.8036734693880
  984.5531486880470
  972.8884131611830
  1056.797211281010
  1255.1133239551500
  
  **RMA:**
  NaN
  NaN
  NaN
  NaN
  NaN
  NaN
  NaN
  4110.605714285710
  4186.233469387760
  4403.912973760930
  4624.7854060808000
  4845.527490926400
  5202.596420794060
  5289.515503537760
  
  
  To be honest I'm little bit lost and can't find issue cause.
  
  
  P.S. sorry for incorrectly previously opened issue, i clicked "bug" occasionally and topic was like a discussion with other users if anyone seen this.
  