Algebra.js Symbolic Equation Solver

Warnings

• gotcha In versions prior to 0.2.0, solving single-variable equations with an infinite number of solutions would return `undefined`. This behavior changed in 0.2.0 to return `Fraction(1, 1)`.
  Fix: Update to version 0.2.0 or later and adjust logic to handle `Fraction(1, 1)` instead of `undefined` for infinite solutions.
• gotcha Versions prior to 0.2.4 contained a bug where solving quadratic equations with irrational solutions when the 'a' coefficient was greater than 1 yielded incorrect results. Relying on such solutions in older versions would have produced wrong output.
  Fix: Upgrade to version 0.2.4 or newer to ensure correct solving of quadratic equations under these conditions.
• gotcha The parser in versions prior to 0.2.2 incorrectly handled negative numbers (throwing an error) and misinterpreted adjacent parentheses. Code relying on previous buggy parser behavior or error handling for these cases will need adjustment.
  Fix: Upgrade to version 0.2.2 or newer to benefit from improved parser robustness and correct interpretation of negative numbers and adjacent parentheses.
• gotcha `Expression.simplify()` in versions prior to 0.2.1 would sometimes fail to fully simplify expressions consisting only of unsimplified constants, reducing them to two constants instead of a single one. This could lead to unexpected unsimplified numerical results.
  Fix: Update to version 0.2.1 or later to ensure `Expression.simplify()` consistently reduces expressions to their single simplest constant form.

Install

• npm install algebra.js npm
• yarn add algebra.js yarn
• pnpm add algebra.js pnpm

Imports

• algebra
  wrong:

  import algebra from 'algebra.js';

  correct:

  const algebra = require('algebra.js');

  This library is a CommonJS module. The `algebra` object is the main export, containing all constructors and utility methods.
• Expression
  wrong:

  const { Expression } = require('algebra.js');
  // or
  import { Expression } from 'algebra.js';

  correct:

  const algebra = require('algebra.js');
  const expr = new algebra.Expression('x');

  `Expression` is a constructor exposed as a property of the main `algebra` export, not a named export itself.
• Equation
  wrong:

  const { Equation } = require('algebra.js');
  // or
  import { Equation } from 'algebra.js';

  correct:

  const algebra = require('algebra.js');
  const eq = new algebra.Equation(expr, 4);

  `Equation` is a constructor exposed as a property of the main `algebra` export, not a named export itself.
• Fraction
  wrong:

  const { Fraction } = require('algebra.js');
  // or
  import { Fraction } from 'algebra.js';

  correct:

  const algebra = require('algebra.js');
  const frac = new algebra.Fraction(1, 2);

  `Fraction` is a constructor exposed as a property of the main `algebra` export, used for precise fractional arithmetic.
• parse
  wrong:

  const { parse } = require('algebra.js');
  // or
  import { parse } from 'algebra.js';

  correct:

  const algebra = require('algebra.js');
  const exp = algebra.parse("x^2 + 4 * x + 4");

  The `parse` utility method is directly available on the main `algebra` object for parsing strings into expressions or equations.

Quickstart

Demonstrates creating expressions, equations, displaying them, solving for a variable, and using the string parser.

const algebra = require('algebra.js');

// Create an expression
let expr = new algebra.Expression("x");
expr = expr.subtract(3);
expr = expr.add("x");

console.log(expr.toString()); // Expected: 2x - 3

// Create an equation from the expression
const eq = new algebra.Equation(expr, 4);

console.log(eq.toString()); // Expected: 2x - 3 = 4

// Solve the equation for 'x'
const x = eq.solveFor("x");

console.log("x = " + x.toString()); // Expected: x = 7/2

// Use the parser to create an equation directly from a string
const quadraticEq = algebra.parse("x^2 + 4 * x + 4 = 0");
console.log(quadraticEq.toString()); // Expected: x^2 + 4x + 4 = 0