functionx 1.0.0

A powerful equation parser and solver for Dart. Parse expressions, extract variables, evaluate, solve equations, and perform symbolic calculus with a comprehensive physics constants library.

functionx

A powerful equation parser and solver for Dart — f(x) for your code.

Features

• 🧮 Expression Parsing - Parse mathematical expressions with explicit operators
• 📊 Variable Extraction - Extract all variables from an expression
• 🔢 Expression Evaluation - Evaluate expressions with variable substitution
• ⚡ Equation Solving - Solve equations algebraically and numerically
• 📈 Symbolic Calculus - Differentiation and integration (CAS)
• 🔬 Physical Constants - Comprehensive collection of physics and math constants

Installation

Add to your pubspec.yaml:

dependencies:
  functionx: ^2.0.0

Quick Start

import 'package:functionx/functionx.dart';

void main() {
  // Extract variables from an equation
  final vars = ExpressionParser.extractVariables('y = m*x + b');
  print(vars); // ['b', 'm', 'x', 'y']

  // Evaluate an expression
  final result = Evaluator.evaluate('x^2 + 2*x + 1', {'x': 3});
  print(result); // 16.0

  // Solve an equation
  final solution = Solver.solve(
    'F = m*a',
    {'F': 10, 'm': 2},
    solveFor: 'a',
  );
  print(solution.value); // 5.0

  // Use physical constants
  final c = Constants.speedOfLight;
  print('${c.name}: ${c.value} ${c.unit}'); // Speed of Light: 299792458 m/s

  // Symbolic differentiation
  final derivative = Cas.differentiate('x^2', 'x');
  print(derivative); // '2.0 * x'
}

Expression Syntax

This parser uses explicit operator notation:

✅ Correct	❌ Incorrect
2*x + 3	2x + 3
a*b*c	abc
sin(x)^2	sin^2(x)

Supported Operators

Operator	Description
+	Addition
-	Subtraction
*	Multiplication
/	Division
^	Exponentiation

Supported Functions

Function	Description
sin(x)	Sine
cos(x)	Cosine
tan(x)	Tangent
asin(x)	Arc sine
acos(x)	Arc cosine
atan(x)	Arc tangent
sqrt(x)	Square root
abs(x)	Absolute value
log(x)	Natural logarithm
ln(x)	Natural logarithm
exp(x)	Exponential
pow(x, n)	Power

Mathematical Constants

Constant	Value
pi	3.14159...
e	2.71828...
infinity	∞

API Reference

ExpressionParser

// Parse expression or equation
final result = ExpressionParser.parse('y = m*x + b');
print(result.isEquation); // true

// Extract variables
final vars = ExpressionParser.extractVariables('F = m*a');
print(vars); // ['F', 'a', 'm']

Evaluator

// Evaluate with variables
final result = Evaluator.evaluate('x^2 + y', {'x': 3, 'y': 5});
print(result); // 14.0

// Evaluate numeric expression (no variables)
final result = Evaluator.evaluateNumeric('2 + 3 * 4');
print(result); // 14.0

Solver

// Solve for unknown variable
final result = Solver.solve(
  '2*x + 5 = 11',
  {'x': null},
);
print(result.value); // 3.0
print(result.steps); // ['...solution steps...']

// Solve physics equation
final result = Solver.solve(
  'F = m*a',
  {'F': 10, 'm': 2},
  solveFor: 'a',
);
print(result.value); // 5.0

Cas (Computer Algebra System)

// Differentiation
final deriv = Cas.differentiate('x^3', 'x');
print(deriv); // '3.0 * x ^ 2.0'

// Integration
final integral = Cas.integrate('x', 'x');
print(integral); // '0.5*x^2'

// Simplification
final simplified = Cas.simplify('x + x');
print(simplified); // '2.0 * x'

Constants

A comprehensive collection of physical and mathematical constants.

// Access by property
final c = Constants.speedOfLight;
print(c.value);  // 299792458
print(c.symbol); // c
print(c.unit);   // m/s
print(c.name);   // Speed of Light

// Get by key
final g = Constants.get('G');
print(g?.value); // 6.6743e-11

// List all constants in a category
final fundamental = Constants.byCategory('fundamental');

// Search constants
final results = Constants.search('mass');

Available Categories

Category	Examples
mathematical	π, e, φ (golden ratio), √2
fundamental	Speed of light, Planck constant, Gravitational constant
electromagnetic	Elementary charge, Vacuum permittivity, Coulomb constant
atomic	Electron mass, Proton mass, Bohr radius, Fine structure constant
thermodynamic	Boltzmann constant, Gas constant, Avogadro number
earth	Standard gravity, Earth mass, Earth radius
celestial	Sun mass, Astronomical unit, Light year

Common Constants

Property	Key	Symbol	Value
Constants.speedOfLight	SPEED_OF_LIGHT	c	299792458 m/s
Constants.planck	PLANCK	h	6.626e-34 J⋅s
Constants.gravitationalConstant	G	G	6.674e-11 N⋅m²/kg²
Constants.boltzmann	K_B	kB	1.381e-23 J/K
Constants.avogadro	N_A	NA	6.022e23 1/mol
Constants.standardGravity	G_EARTH	g	9.807 m/s²
Constants.elementaryCharge	E_CHARGE	e	1.602e-19 C
Constants.pi	PI	π	3.14159...
Constants.e	EULER	e	2.71828...

License

MIT License - see LICENSE for details.