Peaks/troughs defined by Eqs (9) and (10) together with the peak/trough indicators of FTSE 100 Index.

<p>The peaks and troughs are marked by red circles and green crosses respectively. The time when peaks and troughs occurred are also indicated in vertical dash-dotted lines and dashed lines respectively. The sample data are the daily close price of these four indices for 20 years from Jul. 8, 1994 to Jul. 7, 2014.