MathEvaluator 1.0.0

Math Expression Evaluator in .NET

Overview

MathEvaluator is a .NET library that allows you to evaluate any mathematical expressions from a string dynamically.

Features

• Supports different mathematical contexts, such as scientific, programming, and other custom contexts.
• Evaluates to double or decimal.
• Provides variable support within expressions.
• Extensible with custom functions.
• Fast and comprehensive. More than 1000 tests are passed, including complex math expressions (for example, -3^4sin(-π/2) or sin-3/cos1).

Installation

    dotnet add package MathEvaluator

Alternatively, you can install the package using the NuGet Package Manager Console:

    Install-Package MathEvaluator

Perfomance

This math expression evaluator is designed for exceptional performance by leveraging modern .NET features and best practices, which is why it targets .NET Standard 2.1 or higher.

This high-performance evaluator stands out due to its use of ReadOnlySpan<char>, avoidance of regular expressions, and reliance on static methods. These design choices collectively ensure minimal memory allocation, fast parsing, and efficient execution.

The evaluator uses recursive method calls to handle mathematical operations based on operator precedence and rules. This approach avoids the overhead associated with stack or queue data structures.

The evaluator uses a prefix tree, also known as a trie (pronounced "try"), for efficient searching of variables and functions by their keys (names) when providing a specific mathematical context or adding custom variables and functions is required.

Let's compare, for example, performance of calculating the mathematical expression:

    22888.32 * 30 / 323.34 / .5 - -1 / (2 + 22888.32) * 4 - 6

Below are the results of the comparison with the NCalc library:

How to use

Examples of using string extentions:

    "22888.32 * 30 / 323.34 / .5 - -1 / (2 + 22888.32) * 4 - 6".Evaluate();

    "22888.32 * 30 / 323.34 / .5 - -1 / (2 + 22888.32) * 4 - 6".EvaluateDecimal();

    "$22,888.32 * 30 / 323.34 / .5 - - 1 / (2 + $22,888.32) * 4 - 6".Evaluate(new CultureInfo("en-US"));

    "22’888.32 CHF * 30 / 323.34 / .5 - - 1 / (2 + 22’888.32 CHF) * 4 - 6".EvaluateDecimal(new CultureInfo("de-CH"));

    "ln[1/-0.5 + √(1/(0.5^2) + 1)]".Evaluate(new ScientificMathContext());
    
    "ln[1/-0,5 + √(1/(0,5^2) + 1)]".Evaluate(new ScientificMathContext(), new CultureInfo("fr"));
    
    "ln[1/-0.5 + √(1/(0.5^2) + 1)]".EvaluateDecimal(new ScientificMathContext());
    
    "ln[1/-0,5 + √(1/(0,5^2) + 1)]".EvaluateDecimal(new ScientificMathContext(), new CultureInfo("fr"));
    
    "4 % 3".Evaluate(new ProgrammingMathContext());
    
    "4 mod 3".EvaluateDecimal(new ScientificMathContext());

Examples of using static methods:

    MathEvaluator.Evaluate("22888.32 * 30 / 323.34 / .5 - -1 / (2 + 22888.32) * 4 - 6");

    MathEvaluator.EvaluateDecimal("22888.32 * 30 / 323.34 / .5 - -1 / (2 + 22888.32) * 4 - 6");

    MathEvaluator.Evaluate("$22,888.32 * 30 / 323.34 / .5 - - 1 / (2 + $22,888.32) * 4 - 6", new CultureInfo("en-US"));

    MathEvaluator.EvaluateDecimal("22’888.32 CHF * 30 / 323.34 / .5 - - 1 / (2 + 22’888.32 CHF) * 4 - 6", new CultureInfo("de-CH"));
    
    MathEvaluator.Evaluate("ln[1/-0.5 + √(1/(0.5^2) + 1)]", new ScientificMathContext());
    
    MathEvaluator.Evaluate("ln[1/-0,5 + √(1/(0,5^2) + 1)]", new ScientificMathContext(), new CultureInfo("fr"));
    
    MathEvaluator.EvaluateDecimal("ln[1/-0.5 + √(1/(0.5^2) + 1)]", new ScientificMathContext());
    
    MathEvaluator.EvaluateDecimal("ln[1/-0,5 + √(1/(0,5^2) + 1)]", new ScientificMathContext(), new CultureInfo("fr"));
    
    MathEvaluator.Evaluate("4 % 3", new ProgrammingMathContext());
    
    MathEvaluator.EvaluateDecimal("4 mod 3", new ScientificMathContext());

Examples of using an instance of the MathEvaluator class:

    new MathEvaluator("22888.32 * 30 / 323.34 / .5 - -1 / (2 + 22888.32) * 4 - 6").Evaluate();

    new MathEvaluator("22888.32 * 30 / 323.34 / .5 - -1 / (2 + 22888.32) * 4 - 6").EvaluateDecimal();

    new MathEvaluator("$22,888.32 * 30 / 323.34 / .5 - - 1 / (2 + $22,888.32) * 4 - 6").Evaluate(new CultureInfo("en-US"));

    new MathEvaluator("22’888.32 CHF * 30 / 323.34 / .5 - - 1 / (2 + 22’888.32 CHF) * 4 - 6").EvaluateDecimal(new CultureInfo("de-CH"));
    
    new MathEvaluator("ln[1/-0.5 + √(1/(0.5^2) + 1)]", new ScientificMathContext()).Evaluate();
    
    new MathEvaluator("ln[1/-0,5 + √(1/(0,5^2) + 1)]", new ScientificMathContext()).Evaluate(new CultureInfo("fr"));
    
    new MathEvaluator("ln[1/-0.5 + √(1/(0.5^2) + 1)]", new ScientificMathContext()).EvaluateDecimal();
    
    new MathEvaluator("ln[1/-0,5 + √(1/(0,5^2) + 1)]", new ScientificMathContext()).EvaluateDecimal(new CultureInfo("fr"));
    
    new MathEvaluator("4 % 3", new ProgrammingMathContext()).Evaluate();
    
    new MathEvaluator("4 mod 3", new ScientificMathContext()).EvaluateDecimal();

Examples of using custom variables or functions:

    var x1 = 0.5;
    var x2 = -0.5;
    var sqrt = Math.Sqrt;
    Func<double, double> ln = Math.Log;

    var value1 = "ln(1/-x1 + sqrt(1/(x2*x2) + 1))"
        .Bind(new { x1, x2, sqrt, ln })
        .Evaluate();

    var value2 = "ln(1/-x1 + Math.Sqrt(1/(x2*x2) + 1))"
        .BindVariable(0.5, "x1")
        .BindVariable(-0.5, "x2")
        .BindFunction(Math.Sqrt)
        .BindFunction(Math.Log, "ln")
        .Evaluate();

Example of using custom context:

    var context = new MathContext();
    context.BindVariable(0.5, "x1");
    context.BindVariable(-0.5, "x2");
    context.BindFunction(Math.Sqrt);
    context.BindFunction(Math.Log, "ln");

    "ln(1/-x1 + Math.Sqrt(1/(x2*x2) + 1))"
        .SetContext(context)
        .Evaluate();

Supported math functions, operators, and constants

Scientific Math Context (using ScientificMathContext class):

Programming Math Context (using ProgrammingMathContext class):

How to evaluate C# math string expression

DotNetStandartMathContext (inherits the ProgrammingMathContext class) is the .NET Standart 2.1 programming math context supports all constants and functions provided by the System.Math class.

Example of evaluating C# expression:

    "-2 * Math.Log(1/0.5f + Math.Sqrt(1/Math.Pow(0.5d, 2) + 1L)".Evaluate(new DotNetStandartMathContext());

NOTE: More math functions could be added to the math expression evaluator based on user needs.

Contributing

Contributions are welcome! Please fork the repository and submit pull requests for any enhancements or bug fixes. If you enjoy my work and find it valuable, please consider becoming my sponsor on GitHub. Your support will enable me to share more open-source code. Together, we can make a positive impact in the developer community!

License

This project is licensed under the Apache License, Version 2.0 - see the LICENSE file for details.

Contact

If you have any questions or suggestions, feel free to open an issue or contact me directly.