Summary
BullsPower is RTTA's streaming implementation of Alexander Elder's bulls
power: the distance of the bar high above an EMA of close. It is the bull
component of ElderRayIndex, exposed as a single scalar for retail-style APIs.
Update API
value = rtta.BullsPower(window=13, fillna=True).update(high, close)
The update(...) call consumes high and close. advance(...) uses the same
inputs without returning a Python value. Scalar batch(high, close) returns a
NumPy array.
Theory Of Operation
Elder models "bulls" as how far buyers managed to push the high relative to a
consensus value of close (the EMA). Large positive bulls power means the high
stands well above the smoothed close; values near zero mean the high is pinned
to the EMA. Combined with BearsPower (or ElderRayIndex), it forms the classic
Elder-ray picture of bull and bear pressure.
Recurrence
Let \(c_t\) be close, \(h_t\) be high, and \(n\) be window. Let
\(\operatorname{EMA}_n\) be RTTA's exponential moving average of close.
Implementation Notes
The recurrence is implemented in src/rtta/indicator.cpp in class BullsPower.
On the same EMA seed path it matches ElderRayIndex.bull_power.