mathjs/lib/function/arithmetic/mod.js

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser with support for symbolic computation, comes with a large set of built-in functions and constants, and offers an integrated solution to work with dif

'use strict';

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

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

  var algorithm02 = load(require('../../type/matrix/utils/algorithm02'));
  var algorithm03 = load(require('../../type/matrix/utils/algorithm03'));
  var algorithm05 = load(require('../../type/matrix/utils/algorithm05'));
  var algorithm11 = load(require('../../type/matrix/utils/algorithm11'));
  var algorithm12 = load(require('../../type/matrix/utils/algorithm12'));
  var algorithm13 = load(require('../../type/matrix/utils/algorithm13'));
  var algorithm14 = load(require('../../type/matrix/utils/algorithm14'));
  /**
   * Calculates the modulus, the remainder of an integer division.
   *
   * For matrices, the function is evaluated element wise.
   *
   * The modulus is defined as:
   *
   *     x - y * floor(x / y)
   *
   * See https://en.wikipedia.org/wiki/Modulo_operation.
   *
   * Syntax:
   *
   *    math.mod(x, y)
   *
   * Examples:
   *
   *    math.mod(8, 3)                // returns 2
   *    math.mod(11, 2)               // returns 1
   *
   *    function isOdd(x) {
   *      return math.mod(x, 2) != 0
   *    }
   *
   *    isOdd(2)                      // returns false
   *    isOdd(3)                      // returns true
   *
   * See also:
   *
   *    divide
   *
   * @param  {number | BigNumber | Fraction | Array | Matrix} x Dividend
   * @param  {number | BigNumber | Fraction | Array | Matrix} y Divisor
   * @return {number | BigNumber | Fraction | Array | Matrix} Returns the remainder of `x` divided by `y`.
   */

  var mod = typed('mod', {
    'number, number': _mod,
    'BigNumber, BigNumber': function BigNumberBigNumber(x, y) {
      return y.isZero() ? x : x.mod(y);
    },
    'Fraction, Fraction': function FractionFraction(x, y) {
      return x.mod(y);
    },
    'SparseMatrix, SparseMatrix': function SparseMatrixSparseMatrix(x, y) {
      return algorithm05(x, y, mod, false);
    },
    'SparseMatrix, DenseMatrix': function SparseMatrixDenseMatrix(x, y) {
      return algorithm02(y, x, mod, true);
    },
    'DenseMatrix, SparseMatrix': function DenseMatrixSparseMatrix(x, y) {
      return algorithm03(x, y, mod, false);
    },
    'DenseMatrix, DenseMatrix': function DenseMatrixDenseMatrix(x, y) {
      return algorithm13(x, y, mod);
    },
    'Array, Array': function ArrayArray(x, y) {
      // use matrix implementation
      return mod(matrix(x), matrix(y)).valueOf();
    },
    'Array, Matrix': function ArrayMatrix(x, y) {
      // use matrix implementation
      return mod(matrix(x), y);
    },
    'Matrix, Array': function MatrixArray(x, y) {
      // use matrix implementation
      return mod(x, matrix(y));
    },
    'SparseMatrix, any': function SparseMatrixAny(x, y) {
      return algorithm11(x, y, mod, false);
    },
    'DenseMatrix, any': function DenseMatrixAny(x, y) {
      return algorithm14(x, y, mod, false);
    },
    'any, SparseMatrix': function anySparseMatrix(x, y) {
      return algorithm12(y, x, mod, true);
    },
    'any, DenseMatrix': function anyDenseMatrix(x, y) {
      return algorithm14(y, x, mod, true);
    },
    'Array, any': function ArrayAny(x, y) {
      // use matrix implementation
      return algorithm14(matrix(x), y, mod, false).valueOf();
    },
    'any, Array': function anyArray(x, y) {
      // use matrix implementation
      return algorithm14(matrix(y), x, mod, true).valueOf();
    }
  });
  mod.toTex = {
    2: "\\left(${args[0]}".concat(latex.operators['mod'], "${args[1]}\\right)")
  };
  return mod;
  /**
   * Calculate the modulus of two numbers
   * @param {number} x
   * @param {number} y
   * @returns {number} res
   * @private
   */

  function _mod(x, y) {
    if (y > 0) {
      // We don't use JavaScript's % operator here as this doesn't work
      // correctly for x < 0 and x === 0
      // see https://en.wikipedia.org/wiki/Modulo_operation
      return x - y * Math.floor(x / y);
    } else if (y === 0) {
      return x;
    } else {
      // y < 0
      // TODO: implement mod for a negative divisor
      throw new Error('Cannot calculate mod for a negative divisor');
    }
  }
}

exports.name = 'mod';
exports.factory = factory;