title: tbats error from -Inf Values
body: <p>My end goal is to create a forecast from a tbats model that will not forecast negative values.  So I'm using the code below to force the boxcox transformation to use lambda = 0.  The problem I'm running in to is that my dataTs has 0s in it which produce log(0) = -Inf, and tbats throws the error message below when you pass it -Inf.  Any tips would be greatly appreciated.</p>
  
  <pre><code>Code:
  
  Log_TBATS&lt;-function(y){
                          x &lt;- log(y)
                          fit &lt;- tbats(x, use.box.cox=FALSE)
                          fit$lambda &lt;- 0
                          fit$control$use.box.cox &lt;- TRUE
                          fc &lt;- forecast(fit,h=20)
                          fc$x &lt;- exp(x)
                          fc
  }
  
  
  
  Log_TBATS(dataTs)
  
  
  Trace back:
  
  Error in checkForRemoteErrors(val) : 
  3 nodes produced errors; first error: NA/NaN/Inf in 'y' 
  7. stop(count, " nodes produced errors; first error: ", firstmsg, 
      domain = NA) 
  6. checkForRemoteErrors(val) 
  5. dynamicClusterApply(cl, fun, length(x), argfun) 
  4. clusterApplyLB(clus, c(1:nrow(control.array)), parFilterSpecifics, 
  y = y, control.array = control.array, seasonal.periods = seasonal.periods, 
  use.arma.errors = use.arma.errors, init.box.cox = init.box.cox, 
  bc.lower = bc.lower, bc.upper = bc.upper, ...) 
  3. bats(as.numeric(y), use.box.cox = use.box.cox, use.trend = use.trend, 
  use.damped.trend = use.damped.trend, use.arma.errors = use.arma.errors, 
  use.parallel = use.parallel, num.cores = num.cores, bc.lower = bc.lower, 
  bc.upper = bc.upper, ...) 
  2. tbats(x, use.box.cox = FALSE) 
  1. Log_TBATS(dataTs) 
  
  
  
  
  
  dput(dataTs)
  c(2, 2, 1, 0, 0, 1, 2, 0, 1, 4, 8, 7, 7, 6, 5, 5, 4, 3, 1, 5, 
  9, 5, 3, 2, 0, 0, 1, 0, 1, 0, 0, 2, 1, 5, 6, 5, 3, 2, 5, 4, 6, 
  5, 3, 4, 2, 5, 2, 1, 0, 4, 1, 2, 2, 2, 1, 1, 2, 1, 2, 7, 7, 3, 
  7, 3, 3, 2, 0, 4, 1, 3, 4, 1, 3, 0, 1, 3, 1, 0, 1, 3, 2, 4, 4, 
  2, 4, 5, 4, 3, 8, 3, 3, 5, 4, 3, 1, 1, 1, 2, 1, 1)
  </code></pre>