You can calculate x from a given date, e.g. x from Feb 22 in Python:
>>> from datetime import date
>>> x = (date(2014, 2, 22) - date(2009, 1, 3)).days
>>> x
1876
The trend point can be calculated online using the wolframalpha computational search engine in two steps:
first, get the number of days since 2009-1-3:
https://www.wolframalpha.com/input/?i=number+of+days+since+2009-01-03This URL will work for any "today"
next, using that number (today it was 1880), replace it in the following search term:
https://www.wolframalpha.com/input/?i=10+%5E+%280.003073+*+1880+-+2.909514%29
**remember to replace the 1880 number with today's correct number and run the search again.
The result is today's trendline price in USD.
Note: if someone can figure out how to encapsulate the results of the first search URL directly into the second, then this could be a single bookmark-able URL to return today's trendline value.
edit* the forum software was butchering my second URL. I had to embed it into a code tag to get it to show up properly. You will have to copy and paste it into a new browser window to use it. Again, anyone know a fix for that problem?