Negative values for multiplicative holt-winters

[plowel]

Hi, could you clarify why negative values and zeros are not allowed for the multiplicative holt-winters exponential smoothing? I tried to read over the documentation, but couldn't find the explanation for that.
I used the same methodology in Statistica and it worked with negative values and zeros in the input series.

I currently use Eviews7.

Thank you.

[kiber_master]

Hello!
I'm interested in this question too, why don't you answer?