st: calculating the difference in logs

["Data Analytics Corp." <walt@dataanalyticscorp.com>]

Hi,

Suppose I have a time series on annual sales.  I'd like to calculate the 
year-over-year percent change using the difference in the natural logs.  
I tried
    g pct = d.ln(sales)

but I got an error message "unknown function d.ln()"

Then I tried

    g logg = ln(sales)
    g pct = d.logg

and I got the right answer.  I'd like to use just the one line statement 
as in the first example.  Can this be done?  Am I missing something?  It 
seems that it should work.
Thanks,

Walt

________________________

Walter R. Paczkowski, Ph.D.
Data Analytics Corp.
44 Hamilton Lane
Plainsboro, NJ 08536
________________________
(V) 609-936-8999
(F) 609-936-3733
walt@dataanalyticscorp.com
www.dataanalyticscorp.com
_____________________________________________________

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