title: how to get the arima model's variance of white noise's at each points in R?
body: <p>I have trained a ARIMA(1,0,2)(0,1,1)[7] just like that:(use R's function Arima{forecast} )</p>
  
  <pre><code> &gt;test.arima=Arima(x=tsx.rd_lm, order=c(1,0,2), seasonal=list(order=c(0,1,1),period=7),fixed=c(NA,0,NA,NA), lambda=0.9533674)
  
   &gt;test.arima
  Box Cox transformation: lambda= 0.9533674 
  
  Coefficients:
  
       ar1  ma1     ma2     sma1
    0.6089    0  0.2314  -0.8650
  s.e.  0.0426    0  0.0513   0.0383
  sigma^2 estimated as 170690303:  log likelihood=-4908.65
  AIC=9825.3   AICc=9825.43   BIC=9845.84
  </code></pre>
  
  <p>How ever, the sigma value {170690303} is terriable, so I hope get each points white noise (variance) to check. After all, maybe some xreg parameter could be find more effectivly. 
  @ADD: a brief of the data:<code>Named num [1:241] 732499 724785 717221 709805 702539 ...</code>
  @ADD: how ever, <code>test.arima</code> doest't offer the names like a <code>lm</code> class in R. 
  So, just like get the lm model's residuals at each point by residuals <code>lm.my$residuals</code>, How to get the arima class's white noise's at each points in R? </p>
  
  <p>Thanks!</p>