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Velocity Tracker Trend
NewFreeAlpha-beta velocity trend with a tracking-error trailing stop
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- Language
- QuaScript
- Engine
- Native C++, incremental on live ticks
- Rendering
- Canvas
- Placement
- Price overlay
- Settings
- 5
- Plots
- 5
- Lines of code
- 82
- Source
- presets/strategy/velocity_tracker_trend.qs
About
Trend following on a tracked velocity instead of a moving-average cross. An alpha-beta filter (the steady-state constant-velocity Kalman filter) estimates price level and velocity together. A trade starts when the velocity, in ATR per bar, passes a threshold while acceleration agrees, so the system joins moves that are speeding up rather than any drift. The stop trails at a multiple of the tracking error below the tracked level. Entry: velocity above `v_in` ATR per bar with positive smoothed acceleration and price inside the two-sigma envelope (no chasing shocks); mirror for shorts. Exit: trailing stop at the level minus `k_err` tracking errors (never loosened), or velocity back through zero. Risk: 1 % per trade at the initial stop.
What it draws
Price overlay · counted from the engine's plot table and the script's draw calls
Series
- Line1 visible · 3 helperTracked level
- Step line1Trailing stop
- Band fills (render.band calls)1
Signal marks
Drawings and chart effects
- Dashboard tables1 created
How it runs
From source to the live chart, for this script
- 1Compile
The QuaScript compiler checks the 82-line script (72 lines of code) and lowers it for the native C++ engine. Compile errors point at the exact line and column.
- 2Place
The header sets
overlay = true, so everything is drawn on the price chart, on the same scale as the candles. - 3Compute
The script runs once per bar, oldest to newest. 5
persistvariables keep state (objects, counters) across bars. - 4Stay live
On the terminal the script keeps one live engine session: a tick rolls the forming bar back to its checkpoint and re-executes only that bar, and new bars are appended, so history is never rerun while the market moves. The live result is identical to a full run.
- 5Render
The results are handed to the chart: series on Canvas.
- 6Tune
5 settings in 3 groups appear in the chart's settings dialog. Changing one reruns the engine with the new value.
Rendering
This script draws on Canvas
The browser's modern GPU API. The chart uploads every line, band and mark of the script as GPU buffers and draws them in one pass, so dense heatmaps and dozens of series stay smooth while you pan and zoom. Without WebGPU support the chart's GPU layer falls back to WebGL 2, then Canvas 2D.
GPU drawing through WebGL 2, available in every current browser. Used for chart-native profiles and for series that ask for it with backend = "webgl". Fast for large numbers of bars and wide fills.
The browser's 2D drawing API. Text-heavy and object-style output (dashboard tables, zones, tags, segments), candle colors and backgrounds are painted by the QuaScript layer, a Canvas 2D surface over the chart. Series use Canvas when the script's header does not ask for a GPU.
- • 5 plotted series
- • 1 band fill call
- • 2 signal mark types
- • 1 dashboard tables (QuaScript layer)
Settings
5 settings, grouped as in the chart's settings dialog
| Setting | Type | Default | Range / options | Id |
|---|---|---|---|---|
| Alpha (level gain) | Number | 0.18 | 0.01 – 0.9, step 0.01 | alpha_level_gain |
| Beta (velocity gain) | Number | 0.006 | 0.0005 – 0.5, step 0.0005 | beta_velocity_gain |
| Error window | Integer | 50 | 5 – 1000 | error_window |
| Setting | Type | Default | Range / options | Id |
|---|---|---|---|---|
| Entry velocity (ATR / bar) | Number | 0.08 | 0.005 – 1, step 0.005 | entry_velocity_atr_bar |
| Setting | Type | Default | Range / options | Id |
|---|---|---|---|---|
| Trailing stop (tracking errors) | Number | 4 | 0.5 – 10, step 0.1 | trailing_stop_tracking_errors |
Script
packages/quascript/presets/strategy/velocity_tracker_trend.qs
Header
strategy "Velocity Tracker Trend" {
overlay = true
capital = 100000
commission = 0.05
slippage = 1
sizing = risk_percent
max_leverage = 1
size = 1
pyramiding = 1
}- Total lines
- 82
- Code lines
- 72
- Comment lines
- 9
- Helper functions
- 0
- Loops
- 0
- Persistent variables
- 5
- Higher-interval feeds
- 0
- Engine plots
- 5
Built with
ta.atrta.emastat.stdevmath.absmath.clampmath.is_namath.maxmath.minviz/premium
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