McClellanSummationIndex

The McClellan Summation Index — the running cumulative sum of the McClellan Oscillator. Where the oscillator measures breadth momentum, the summation index integrates it into a longer-term breadth trend.

Quick reference

Item	Value
Family	Market Breadth
Input type	CrossSection — the per-symbol state of the whole universe
Output type	f64 (cumulative; may be negative)
Output range	unbounded; centred on 0
Default parameters	none (fixed 19/39 smoothing)
Warmup period	1
Interpretation	Long-term breadth trend

Formula

osc = McClellanOscillator(tick)   # 19/39 EMA spread of ratio-adjusted net advances
sum = sum + osc                   # cumulative

The summation index embeds a McClellanOscillator and adds its value on every tick. Because the oscillator seeds to 0.0 on the first tick, the summation index also starts at 0.0 and is defined from the first update. It behaves like a slow, smoothed advance/decline line. Stateful and O(universe size) per tick. See crates/wickra-core/src/indicators/mcclellan_summation_index.rs.

Parameters

None — inherits the oscillator's fixed 19/39 smoothing. Construct with McClellanSummationIndex::new().

Parameter	Type	Default	Source
—	—	—	None.

Inputs / Outputs

Indicator<Input = CrossSection, Output = f64>:

use wickra::{CrossSection, Indicator, McClellanSummationIndex};

const _: fn(&mut McClellanSummationIndex, CrossSection) -> Option<f64> =
    <McClellanSummationIndex as Indicator>::update;

The bindings pass a tick as four equal-length parallel arrays:

• Python: update(change, volume, new_high, new_low); batch(...) returns a 1-D ndarray.
• Node: update(change, volume, newHigh, newLow); batch returns number[].
• WASM: update(change, volume, newHigh, newLow) only; flag arrays are numeric.

Warmup

warmup_period() == 1; the embedded oscillator seeds on tick one, so the summation index is 0.0 on the first tick and defined thereafter (tests accessors_and_metadata, first_tick_starts_at_zero).

Edge cases

• First tick. The oscillator seeds to 0.0, so the index starts at 0.0 (test first_tick_starts_at_zero).
• Accumulation. The index adds each oscillator value (test accumulates_the_oscillator, worked values 0 -> -50 -> -117.5).
• Reset. reset() clears both the index and the embedded oscillator, which re-seeds on the next tick (test reset_clears_state).
• Invalid / empty universe. Rejected at construction by CrossSection::new.

Examples

Rust

use wickra::{CrossSection, Indicator, McClellanSummationIndex, Member};

let mut msi = McClellanSummationIndex::new();
let tick = CrossSection::new(
    vec![
        Member::new(1.0, 10.0, false, false),
        Member::new(-1.0, 10.0, false, false),
    ],
    0,
)?;
// First tick: oscillator seeds to 0, so the summation index is 0.
assert_eq!(msi.update(tick), Some(0.0));

Python

import wickra as ta

msi = ta.McClellanSummationIndex()
print(msi.update([1.0, -1.0], [10.0, 10.0], [False, False], [False, False]))
# 0.0   (seed)

Node

const { McClellanSummationIndex } = require('wickra');

const msi = new McClellanSummationIndex();
console.log(msi.update([1.0, -1.0], [10, 10], [false, false], [false, false]));
// 0

Streaming

import wickra as ta

msi = ta.McClellanSummationIndex()
flags = [False] * 4
vol = [10.0] * 4
print(msi.update([1.0, 1.0, 1.0, -1.0], vol, flags, flags))    # 0.0    (osc 0)
print(msi.update([-1.0, -1.0, -1.0, 1.0], vol, flags, flags))  # -50.0  (osc -50)
print(msi.update([1.0, 1.0, -1.0, -1.0], vol, flags, flags))   # -117.5 (osc -67.5)

Interpretation

The Summation Index is the McClellan trend gauge.

1. Above / below zero. Sustained positive readings mark a bull breadth regime; sustained negative, a bear regime.
2. Zero-line crosses. A cross of zero is read as a major breadth trend change.
3. Extremes. Very high or low levels mark overbought/oversold breadth that often precedes a turn.

Common pitfalls

• Path-dependent. Like any cumulative series, the absolute level depends on the starting point and the history fed in — compare slopes and zero-crosses, not raw levels across runs.
• Ratio-adjusted base. Inherits the oscillator's RANA basis, so it is universe- size independent but will not match a raw-net Summation Index value-for-value.
• Universe must be stable. Changing membership distorts the underlying RANA.

References

• McClellan, S. & McClellan, M. Patterns for Profit — the McClellan Oscillator and Summation Index.

See also

• Indicator-McClellanOscillator — the oscillator this index accumulates.
• Indicators-Overview — the full taxonomy.