mathjs/lib/function/relational/equal.js

'use strict';

function factory (type, config, load, typed) {
  
  var matrix = load(require('../../type/matrix/function/matrix'));
  var equalScalar = load(require('./equalScalar'));

  var algorithm03 = load(require('../../type/matrix/utils/algorithm03'));
  var algorithm07 = load(require('../../type/matrix/utils/algorithm07'));
  var algorithm12 = load(require('../../type/matrix/utils/algorithm12'));
  var algorithm13 = load(require('../../type/matrix/utils/algorithm13'));
  var algorithm14 = load(require('../../type/matrix/utils/algorithm14'));

  var latex = require('../../utils/latex');

  /**
   * Test whether two values are equal.
   *
   * The function tests whether the relative difference between x and y is
   * smaller than the configured epsilon. The function cannot be used to
   * compare values smaller than approximately 2.22e-16.
   *
   * For matrices, the function is evaluated element wise.
   * In case of complex numbers, x.re must equal y.re, and x.im must equal y.im.
   *
   * Values `null` and `undefined` are compared strictly, thus `null` is only
   * equal to `null` and nothing else, and `undefined` is only equal to
   * `undefined` and nothing else. Strings are compared by their numerical value.
   *
   * Syntax:
   *
   *    math.equal(x, y)
   *
   * Examples:
   *
   *    math.equal(2 + 2, 3);         // returns false
   *    math.equal(2 + 2, 4);         // returns true
   *
   *    var a = math.unit('50 cm');
   *    var b = math.unit('5 m');
   *    math.equal(a, b);             // returns true
   *
   *    var c = [2, 5, 1];
   *    var d = [2, 7, 1];
   *
   *    math.equal(c, d);             // returns [true, false, true]
   *    math.deepEqual(c, d);         // returns false
   *
   *    math.equal("1000", "1e3");    // returns true
   *    math.equal(0, null);          // returns false
   *
   * See also:
   *
   *    unequal, smaller, smallerEq, larger, largerEq, compare, deepEqual
   *
   * @param  {number | BigNumber | boolean | Complex | Unit | string | Array | Matrix} x First value to compare
   * @param  {number | BigNumber | boolean | Complex | Unit | string | Array | Matrix} y Second value to compare
   * @return {boolean | Array | Matrix} Returns true when the compared values are equal, else returns false
   */
  var equal = typed('equal', {
    
    'any, any': function (x, y) {
      // strict equality for null and undefined?
      if (x === null) { return y === null; }
      if (y === null) { return x === null; }
      if (x === undefined) { return y === undefined; }
      if (y === undefined) { return x === undefined; }

      return equalScalar(x, y);
    },

    'SparseMatrix, SparseMatrix': function(x, y) {
      return algorithm07(x, y, equalScalar);
    },

    'SparseMatrix, DenseMatrix': function(x, y) {
      return algorithm03(y, x, equalScalar, true);
    },

    'DenseMatrix, SparseMatrix': function(x, y) {
      return algorithm03(x, y, equalScalar, false);
    },

    'DenseMatrix, DenseMatrix': function(x, y) {
      return algorithm13(x, y, equalScalar);
    },

    'Array, Array': function (x, y) {
      // use matrix implementation
      return equal(matrix(x), matrix(y)).valueOf();
    },

    'Array, Matrix': function (x, y) {
      // use matrix implementation
      return equal(matrix(x), y);
    },

    'Matrix, Array': function (x, y) {
      // use matrix implementation
      return equal(x, matrix(y));
    },

    'SparseMatrix, any': function (x, y) {
      return algorithm12(x, y, equalScalar, false);
    },

    'DenseMatrix, any': function (x, y) {
      return algorithm14(x, y, equalScalar, false);
    },

    'any, SparseMatrix': function (x, y) {
      return algorithm12(y, x, equalScalar, true);
    },

    'any, DenseMatrix': function (x, y) {
      return algorithm14(y, x, equalScalar, true);
    },

    'Array, any': function (x, y) {
      // use matrix implementation
      return algorithm14(matrix(x), y, equalScalar, false).valueOf();
    },

    'any, Array': function (x, y) {
      // use matrix implementation
      return algorithm14(matrix(y), x, equalScalar, true).valueOf();
    }
  });

  equal.toTex = {
    2: '\\left(${args[0]}' + latex.operators['equal'] + '${args[1]}\\right)'
  };

  return equal;
}

exports.name = 'equal';
exports.factory = factory;