Default value of t.window

[Neverstop7]

Hello,
first of all I would like to thank you for creating this package. I find the diagnostic plots of the stlplus package very useful. I'm writing to you because the default value of t.window seems unusual to me. I am not sure if this is done on purpose for some reasons I don't know or if it is just an oversight.

According to the original paper "STL: A Seasonal-Trend Decomposition Procedure Based on Loess" by Cleveland et al., t.window should be set to the smallest odd integer greater or equal to(1.5*period) / (1-(1.5/s.window)(see pages 16-20 and 28). This fact is written in the documentation of the stlplus() function of the stlplus package too:

t. window: If NULL, the default, nextodd(ceiling((1.5*period) / (1-(1.5/s.window)))), is taken.

However the default value of t.windows seems to be different:

fit = stlplus(co2, s.window = 35)
fit$pars$win
  s.window t.window l.window
       35       17       13

The time series is monthly so I would expect a default t.window value equal to 19 instead of 17.

> fit = stlplus(co2, s.window = 15)
> fit$pars$win
  s.window t.window l.window
      15       19       13

And here, I would expect a t.window equal to 21 instead of 19.

Am I missing something?

[Neverstop7]

Any update on this?