Question

I am looking for helpon how to give an exponentially decaying weight according to time. I am writing a small web searching program in c# and want to rank search results according to a time decaying factor.
Can anybody help, i am a newbie to ranking algorithms.

Answer 1

1) Subtract your time values from your reference time (in a real time environment that would be DateTime.Now) to give you a Timespan.
2) Using this Timespan, use one of the Total methods (i.e. TotalHours) to get a double value.
3) If you want to do exponentially decaying weights, then try looking at this:

Exponential Moving Averages