So I am attempting to calculate the Parabolic SAR over FX market data. I understand that the SAR equation is:
SARt = SARt-1 + * [EPt-1 - SARt-1]
with EPt-1 changing depending on if it is a rising or falling SAR but my question is how is the initial/prior SAR (SARt-1) calculated at first with new data or at a transition point (changing from a rising to failing SAR).
Any advice or books with the full mathematical definition would be much appreciated. Many thanks.