MQL4 and MQL5 Programming Articles

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Study the MQL5 language for programming trading strategies in numerous published articles mostly written by you - the community members. The articles are grouped into categories to help you quicker find answers to any questions related to programming: Integration, Tester, Trading Strategies, etc.

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Constructing a Trade Replay Engine in MQL5: Stepping Through Historical Trades Bar by Bar for Manual Review

Constructing a Trade Replay Engine in MQL5: Stepping Through Historical Trades Bar by Bar for Manual Review

An MQL5 script reconstructs closed trades from raw deal history and replays them on the chart bar by bar, drawing entry, exit, stop, target, and an annotation with per‑trade statistics. Four classes separate concerns: a trade data record, history reconstruction with a two‑pass SL/TP lookup and partial‑close aggregation, chart rendering, and a controller with polling‑based keyboard navigation. This enables consistent, fast visual review of each trade in its original candlestick context.
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Detecting and Visualizing Outlier Bars in MQL5 Using Modified Z-Score on OHLCV Features

Detecting and Visualizing Outlier Bars in MQL5 Using Modified Z-Score on OHLCV Features

Abnormal bars inflate mean and standard deviation estimates, distorting ATR, Bollinger Bands, and moving averages. We implement a native MQL5 indicator that detects such bars with the Modified Z-Score applied to four features: body, upper wick, lower wick, and tick volume. The indicator marks flagged bars on the chart and plots a composite score in a separate subwindow, helping you diagnose contamination in rolling-window indicators.
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CSV Data Analysis (Part 1): CSV Export Engine for MQL5 Multi-Core Optimizations

CSV Data Analysis (Part 1): CSV Export Engine for MQL5 Multi-Core Optimizations

Multi-core optimization in MetaTrader 5 can silently drop results when parallel agents contend for the same CSV file. A reusable MQL5 export engine applies an iteration-based spin-lock to acquire the file handle reliably and append rows without loss. It persists custom metrics such as the Sortino Ratio, average trade duration, and signal-quality measures (lag and whipsaws) into a consolidated CSV for downstream analysis.
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Beyond GARCH (Part V): Fitting the Multifractal Spectrum in MQL5

Beyond GARCH (Part V): Fitting the Multifractal Spectrum in MQL5

This article builds the Spectrum Fitter: from tau(q) we compute f(alpha) with a discrete Legendre transform, then fit Normal, Binomial, Poisson, and Gamma spectra under box constraints using BLEIC. The best model by SSE is selected, and its parameters (eg, alpha min, alpha max or alpha_0, gamma) become the cascade inputs for multifractal simulation.
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From Basic to Intermediate: Working with Files in the MetaTrader 5 Sandbox

From Basic to Intermediate: Working with Files in the MetaTrader 5 Sandbox

Do you know what a sandbox is? Do you know how to work with it? If the answer to either of these questions is “no”, read this article to understand the basic operating principle of a sandbox. You will also understand why MetaTrader 5 uses a sandbox to protect the integrity of some of its internal data. The material presented here is purely instructional. Under no circumstances should you treat the application as a final product whose purpose is anything other than studying the concepts presented.
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Comparing Trade Return Distributions with Mann-Whitney U in MQL5

Comparing Trade Return Distributions with Mann-Whitney U in MQL5

A native, dependency-free MQL5 implementation of the Mann-Whitney U test for comparing trade returns across two market regimes. It details rank calculation, tie correction, and a normal-approximation p-value, and pairs the test with a CCanvas box-and-whisker chart and a trade-history extraction script. A verification script is included, and the limits of the normal approximation and independence assumptions are clearly stated for informed use.
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MCMC Sampling Methods — The Metropolis-Hastings Algorithm

MCMC Sampling Methods — The Metropolis-Hastings Algorithm

The Metropolis-Hastings algorithm is a fundamental Markov chain Monte Carlo (MCMC) method that is widely used to approximate posterior distributions in Bayesian inference. This article describes the theoretical foundations of the algorithm, the implementation of the MHSampler class in MQL5, and examples of its application, including an analysis of the resulting samples.
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Neural Networks in Trading: Effective Feature Extraction for Accurate Classification (Final Part)

Neural Networks in Trading: Effective Feature Extraction for Accurate Classification (Final Part)

The Mantis framework transforms complex time series into informative tokens and serves as a reliable foundation for an intelligent trading agent capable of operating in real time.
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Market Microstructure in MQL5 (Part 7): Regime Classification

Market Microstructure in MQL5 (Part 7): Regime Classification

We integrate eleven one-minute microstructure measurements from Parts 2–6 into a composite regime label with confidence and direction. A rule-based RegimeClassifier() assigns one of six regimes—Normal, Stressed, Noisy, Informed, Trending, Mean-Reverting—using empirically derived thresholds from 514 NQ M1 sessions (May 2024–May 2026). The deliverable includes MARKET_REGIME, RegimeAnalysis, and PopulateRegimeAnalysis(), enabling position sizing, stop placement, and signal filtering from a single call.
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Market Simulation: Getting started with SQL in MQL5 (I)

Market Simulation: Getting started with SQL in MQL5 (I)

In today's article we will begin studying the use of SQL in MQL5 code. We will also look at how to create a database. Or, more precisely, how to create a SQLite database file using the features built into MQL5. We will also see how to create a table, and then how to establish a relationship between tables by using primary and foreign keys. All of this, once again, will be done with MQL5. We will see how easy it is to create code that can later be migrated to other SQL implementations by using a class that helps hide the implementation being created. And, most importantly, we will see that at various points we may face the risk that something will go wrong when using SQL. This happens because, in MQL5 code, SQL code will always be placed inside a string.
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From Option Chain to 3D Volatility Surface in MetaTrader 5

From Option Chain to 3D Volatility Surface in MetaTrader 5

This article walks through creating an MT5 indicator that ingests option chains from native symbols or CSV, inverts prices to implied volatility via a hybrid Newton–Raphson/bisection method, and assembles a clean strike–expiry grid. It then renders a shaded, rotatable 3D surface with the platform's DirectX layer, enabling clear, in-terminal analysis of skew and term structure using live or file-based data.
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Exponentially Weighted Covariance Matrix in MQL5: Building an Adaptive Correlation Monitor for Multi-Symbol EAs

Exponentially Weighted Covariance Matrix in MQL5: Building an Adaptive Correlation Monitor for Multi-Symbol EAs

This article builds a constant-memory EW covariance engine and a chart heatmap for monitoring cross-symbol correlations in MQL5. CEWCovariance updates in O(N²) time per bar and exposes covariance/correlation accessors; CHeatmapRenderer shows a five‑symbol matrix with values and colors. You will learn λ-to‑window mapping, how to set a meaningful min_obs warm‑up, and how to size the variance guard epsilon for real FX M1 data.
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How We Built the Most Powerful Machine Learning-Powered Trading Platform: The Evolution of MQL and MetaTrader Through Archives, Forums, and Releases

How We Built the Most Powerful Machine Learning-Powered Trading Platform: The Evolution of MQL and MetaTrader Through Archives, Forums, and Releases

A technical history of MQL evolution: from the limited MQL and MQL II languages, through procedural MQL4, to object-oriented MQL5 with native compilation, rich APIs, and a full-fledged engineering environment. We show here the key capabilities of the language and its integrations with Python, OpenCL, ONNX, OpenBLAS, databases, DirectX, the agentic AI Assistant, and the Model Context Protocol (MCP), which connects AI systems with the terminal, MetaEditor, market data, trading operations, and development tools. This article examines archival materials on the origins of MetaQuotes and MetaTrader, the launch of MQL4.COM and MQL5.COM, the championships, Algo Forge, and their impact on the ecosystem.
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Persistent Key-Value Store in MQL5: Using Flat Files as a Lightweight Database for EA State

Persistent Key-Value Store in MQL5: Using Flat Files as a Lightweight Database for EA State

A lightweight persistence design lets EAs retain counters, flags, and timestamps between terminal restarts. Using only MQL5, CPersistentStore writes a human-readable key=value file in MQL5/Files and serves reads from a CHashMap write-through cache via a typed API. The article analyzes O(1)/O(n) operations, partial‑write risks, and lack of locking, compares with GlobalVariables/SQLite, and provides a demo that reloads state deterministically.
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Building a Modular Fair Value Gap (FVG) Detection Engine in MQL5

Building a Modular Fair Value Gap (FVG) Detection Engine in MQL5

This article introduces a modular Fair Value Gap (FVG) detection engine for MQL5 packaged as a reusable include class, it evaluates imbalance zones on closed bars, applies a Simple True Range average filter to eliminate low-volatility noise, and supports wick-touch and close-through mitigation. A companion diagnostic indicator plots active gaps, and an Expert Advisor template demonstrates automated pullback entries with new-bar execution controls.
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Building a Type-Safe Event Bus in MQL5: Decoupling EA Components Without Global Variables

Building a Type-Safe Event Bus in MQL5: Decoupling EA Components Without Global Variables

A typed publish-subscribe event bus in MQL5 replaces global variables and direct cross-references. Using an abstract listener interface and an enum-indexed subscription table, a signal engine, order manager, and drawdown monitor communicate only through the bus, with no shared state. The article analyzes dispatch overhead, pointer validation, and recursive publish risks, helping you design decoupled, testable EAs.
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Beyond GARCH (Part VI): Fractional Brownian Motion And The Multiplicative Cascade in MQL5

Beyond GARCH (Part VI): Fractional Brownian Motion And The Multiplicative Cascade in MQL5

This article implements the MMAR Simulation Engine that turns fitted parameters (H, distribution, coefficients, sample volatility) into synthetic price paths. It builds multifractal trading time via a multiplicative cascade, synthesizes fractional Brownian motion with Davies–Harte or Cholesky, scales it to target volatility, and composes the process by time deformation. Readers get a reusable MQL5 class, method choices by path length, and validation steps for scenario testing and Monte Carlo use in the next part.
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From Basic to Intermediate: Object Events (IV)

From Basic to Intermediate: Object Events (IV)

In this article, we will complete what was started in the previous one: a fully interactive way to resize objects directly on the chart. Although many people imagine that creating something like this would require much deeper knowledge of MQL5, you will see that, using simple concepts and basic knowledge, we can implement a way to work with objects directly on the chart. This leads to a very interesting and quite compelling result.
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MQL5 Wizard Techniques you should know (Part 99): Using a KD-Tree and an Echo State Network in a Custom Money Management Class

MQL5 Wizard Techniques you should know (Part 99): Using a KD-Tree and an Echo State Network in a Custom Money Management Class

This article lays out 'CMoneyKDTreeESN' custom money management class usable with the MQL5 Wizard, that combines the KD-Tree algorithm and the Echo State Network. We use the KD-Tree on log returns and ATR to give us a risk score, while the ESN tracks recent flow to give us a bounded lot size multiplier. Our class is usable in a variety of Wizard assembled Expert Advisors as shown here with the Envelopes and RSI signals, with a broad objective of modulating exposure in high-volatility and tail-risk environments.
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Analysis of the Impact of Solar and Lunar Cycles on Currency Exchange Rates

Analysis of the Impact of Solar and Lunar Cycles on Currency Exchange Rates

What if lunar cycles and seasonal patterns influence the foreign exchange markets? This article shows how to translate astrological concepts into the language of mathematics and machine learning. I built a Python system with 88 features based on astronomical cycles, trained CatBoost on 15 years of EURUSD data, and obtained some intriguing results. The code is open-source, the methods are verifiable, and the conclusions are unexpected — ancient wisdom meets gradient boosting.
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Porting the Canonical Catch22 Time-Series Feature Set and Testing It on Volatility Regimes

Porting the Canonical Catch22 Time-Series Feature Set and Testing It on Volatility Regimes

We present a native MQL5 implementation of the catch22 feature set: all 22 canonical time-series characteristics in a reusable class validated against pycatch22. Using a leak-free pipeline (chronological split, purging, embargo), we run a three-arm ablation—classic indicators, catch22, and combined—for volatility-regime classification. Finally, we deploy the combined model as a Strategy Tester regime filter to quantify its impact on a simple baseline strategy.
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From Basic to Intermediate: Object Events (I)

From Basic to Intermediate: Object Events (I)

In this article, we will look at three of the six events that MetaTrader 5 can generate when some change occurs to an object on the chart. These events are very useful from the standpoint of user interaction. This is because, without understanding these events, we would have to put in much more effort to maintain a specific chart configuration when trying to manage objects for particular purposes.
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Building a Volume-Based Liquidity Heatmap Indicator in MQL5

Building a Volume-Based Liquidity Heatmap Indicator in MQL5

This article implements an MQL5 Liquidity Heatmap that infers likely liquidation zones from price and volume. It qualifies bars with a rolling volume SMA, computes leverage-based liquidation levels from candle extremes, ranks signals across two volume modes, and manages chart objects (lines and bubbles) that extend until price crosses them, allowing you to highlight potential stop-hunt areas and strengthen structural analysis.
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MQL5 Wizard Techniques you should know (Part 94): Using Reservoir Sampling and Linear Regression in a Custom Trailing Stop Class

MQL5 Wizard Techniques you should know (Part 94): Using Reservoir Sampling and Linear Regression in a Custom Trailing Stop Class

For this article we rotate to a custom MQL5 Wizard class implementation that explores Trailing Stops. Our custom class is ‘CTrailingReservoirLinReg’ that we derive by combining the Reservoir Sampling algorithm with a Linear Regression network. As has been the case throughout these series, this formulation is testable with MQL5 Wizard Assembled Expert Advisors that can be tuned with various entry signals and money management classes.
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Building a Volume-Based Liquidity Heatmap Indicator in MQL5

Building a Volume-Based Liquidity Heatmap Indicator in MQL5

This article implements an MQL5 Liquidity Heatmap that infers likely liquidation zones from price and volume. It qualifies bars with a rolling volume SMA, computes leverage-based liquidation levels from candle extremes, ranks signals across two volume modes, and manages chart objects (lines and bubbles) that extend until price crosses them, allowing you to highlight potential stop-hunt areas and strengthen structural analysis.
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CSV Data Analysis (Part 6): Multi-Broker Result Normalization and Cross-Platform CSV Reconciliation

CSV Data Analysis (Part 6): Multi-Broker Result Normalization and Cross-Platform CSV Reconciliation

This article presents a multi‑broker CSV normalization framework. An MQL5 include file enriches exports with broker metadata. A Python module resolves schema divergences — pip conventions, symbol aliases, time offsets, commission models, and currency denomination — producing a unified canonical dataset. Comparative visualizations of slippage distributions and net‑of‑cost performance enable reliable cross‑platform strategy analysis without silent data corruption.
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MQL5 Wizard Techniques you should know (Part 96): Using Wavelet Thresholding and LSTM Network in a Custom Money Management Class

MQL5 Wizard Techniques you should know (Part 96): Using Wavelet Thresholding and LSTM Network in a Custom Money Management Class

In this article we consider a custom MQL5 Wizard class that processes Money Management. Our custom class is labelled ‘CMoneyWaveletLSTM’, and is developed by combining the Wavelet Thresholding algorithm with an LSTM network. As has been the case throughout these series, the developed model is testable with MQL5 Wizard-Assembled Expert Advisors that can be tuned with different trailing stops and entry Signals classes. We maintain our entry Signal, as in past articles as the built-in 'Envelopes' class and the RSI class.
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Market Simulation: Position View (IV)

Market Simulation: Position View (IV)

Here we will start bringing together different components or applications that were previously completely isolated from each other. Chart Trade, the mouse indicator, and the Expert Advisor had already been linked to one another, but there was still no way to directly display on the chart the positions open on the trading server, which are often managed using a cross-order system. From this point on, this becomes possible, opening the way for various ideas and future implementations. Although we are only beginning to put these components into operation, we already have a direction for further development.
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Beyond GARCH (Part VII): Monte Carlo Volatility Forecasting in MQL5

Beyond GARCH (Part VII): Monte Carlo Volatility Forecasting in MQL5

We implement the CMonteCarlo module that turns the fitted MMAR parameters into a volatility forecast via Monte Carlo. It runs N independent simulations over a chosen horizon and reports mean, median, standard deviation, and a percentile-based 95% confidence interval, with access to per-run values if needed. Adaptive cascade depth selects the minimal k such that b^k covers the horizon, keeping the run fast and consistent.
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Rolling Sharpe Ratio with Statistical Significance Bands in MQL5

Rolling Sharpe Ratio with Statistical Significance Bands in MQL5

This article presents a custom MetaTrader 5 indicator that computes a rolling annualized Sharpe ratio and plots configurable z-score significance bands based on Lo's asymptotic standard error. It uses a circular return buffer with incremental variance to keep O(1) updates. We explain the n^(-1/2) uncertainty scaling, the inflation of intervals at high Sharpe values, and how to set per-instrument annualization for correct deployment.
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Neural Networks in Practice: Practice Makes Perfect

Neural Networks in Practice: Practice Makes Perfect

In today's article, we will see how a simple code change that makes a neuron slightly more specialized can significantly speed up the training stage. After all, once a neuron or neural network, as we will see later, has been trained, the work it performs becomes much faster. We will also discuss a problem that exists but is rarely mentioned.
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From Basic to Intermediate: Object Events (III)

From Basic to Intermediate: Object Events (III)

In this article, we will prepare the foundation for what will be covered in the next publication. We will also look at how to make an OBJ_LABEL object fully interactive for editing and moving. In other words, we can change both the text and the position of the OBJ_LABEL object without opening the Object Properties dialog.
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Streaming MetaTrader 5 Trade Events to a Local HTTP Server Using WinINet in MQL5

Streaming MetaTrader 5 Trade Events to a Local HTTP Server Using WinINet in MQL5

An MQL5 implementation sends trade lifecycle events to a local HTTP service through WinINet with a reusable session and per-request handles. The trade callback only enqueues JSON and returns, while a 500 ms timer drains the queue and retries failed posts, preserving order. A three-stage log policy keeps the Experts tab clear during downtime and summarizes recovery.
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From One Price to Four: Range-Based Volatility Estimators for MetaTrader 5

From One Price to Four: Range-Based Volatility Estimators for MetaTrader 5

Close-to-close volatility ignores the high, the low, and overnight gaps. We build a reusable MQL5 library implementing four range-based estimators from Parkinson to the gap-robust Yang-Zhang, and put it to work in a comparison indicator and a set of adaptive volatility bands.
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From Basic to Intermediate: Object Events (II)

From Basic to Intermediate: Object Events (II)

In this article, we will look at how the last three types of events generated by an object work. Understanding this will be very interesting, because in the end we will do something that may seem crazy to many people, but it is entirely possible and produces a very surprising result.
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Neural Networks in Trading: A Cross-Domain Time Series Forecasting Framework (TimeFound)

Neural Networks in Trading: A Cross-Domain Time Series Forecasting Framework (TimeFound)

In this article, we build the core of the TimeFound intelligent model step by step, adapting it to real-world time series forecasting tasks. If you are interested in the practical implementation of neural network patching algorithms in MQL5, you have come to the right place.
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The Repository Pattern in MQL5: Abstracting Trade History Access for Testable EA Logic

The Repository Pattern in MQL5: Abstracting Trade History Access for Testable EA Logic

Direct calls to the MQL5 History API inside analytics components create hidden terminal dependencies that make isolated testing structurally impossible. This article constructs an ITradeRepository abstraction layer with CLiveTradeRepository and CMockTradeRepository implementations, enabling the same analytics engine and equity curve panel to operate identically against live account data or a deterministic in-memory dataset. Repository injection eliminates direct API coupling, supports offline validation, and confines data source changes to a single implementation class.
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Neural Networks in Trading: Generalizing Time Series Without Data-Specific Dependence (Core Model Modules)

Neural Networks in Trading: Generalizing Time Series Without Data-Specific Dependence (Core Model Modules)

We continue our acquaintance with the Mamba4Cast framework. Today, we will delve into the practical implementation of the proposed approaches. Mamba4Cast was designed not for lengthy warm-up on every new time series, but for immediate deployment. Thanks to the concept of Zero-Shot Forecasting, the model can produce high-quality forecasts on real-world data without additional training or hyperparameter tuning.
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Hierarchical Risk Parity: A Robust Portfolio Allocator and Expert Advisor

Hierarchical Risk Parity: A Robust Portfolio Allocator and Expert Advisor

We implement a Hierarchical Risk Parity allocator in MQL5 as a single class, validate each stage against an independent Python reference, and package it in a rebalancing Expert Advisor. The pipeline covers returns, covariance/correlation, clustering, quasi-diagonalization, and recursive bisection, and contrasts HRP with Markowitz on stressed data. You finish with a verified allocator and an EA ready for basket-level testing.
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Feature Engineering for ML (Part 8): Entropy Features in MQL5

Feature Engineering for ML (Part 8): Entropy Features in MQL5

An MQL5 port of four entropy estimators — Shannon, Plug-In, Lempel-Ziv, and Kontoyiannis — operating on the intrabar tick-rule sequence. CopyTicksRange() limits data to the broker's cached tick window, so features apply to recent bars only. The implementation encodes bid-direction ticks from MqlTick, replaces NumPy-dependent steps with array-based methods, and ships CEntropyFeatures.mqh and EntropyViewer.mq5 for EA and indicator use.