Finding local minima and maxima of a graph

[Bryan McCormick]

Jerry,

Yes, that would be far too many hits and there has to be some scaling 
applied as a filter for that reason. The criteria more precisely is 
"significant" peak and trough values. With significant being the trick. 
For example, is the peak or trough 3 percent or more away.

There is a seasonal and/or trend component to the data. So I think step 
one has to be detrending the series first. If you happen to have a good 
notion of how to write a least-squares fit that would be a great. I'll 
then be able to isolate the peaks and troughs by differencing from that 
line.