Comment 8 for bug 474555

After testing in 10.10 RC, I can confirm that it is still not correctly calculating double-declining depreciation. The calculator's UI has changed, and something about the change has stopped it from presenting the error message; however, the calculation is still not performed correctly. As per my original post, there is no prompt for Salvage. Entering the other three values always calculates to a result of zero, which is obviously incorrect.

A google search turns up several good sources for information regarding calculating double-declining depreciation. A few examples:
http://accountinginfo.com/study/dep/depreciation-01.htm
http://www.ehow.com/how_5098205_calculate-double-declining-depreciation.html
http://www.investopedia.com/articles/06/depreciation.asp
http://en.wikipedia.org/wiki/Depreciation#Declining-balance_method_.28or_Reducing_balance_method.29
http://beginnersinvest.about.com/od/incomestatementanalysis/a/double-declining-balance-depreciation-method.htm

Here is a web-based calculator that computes double-declining depreciation. You can see that it needs four input values to do it correctly. This one also prompts for a fifth value, months in a year. Obviously, it's fine for the calculator to assume 12 months, thus necessitating only four prompts.
http://www.calculatorsoup.com/calculators/financial/depreciation-declining-double.php