mathjs/es/function/matrix/identity.js

import { isBigNumber } from '../../utils/is';
import { resize } from '../../utils/array';
import { isInteger } from '../../utils/number';
import { factory } from '../../utils/factory';
var name = 'identity';
var dependencies = ['typed', 'config', 'matrix', 'BigNumber', 'DenseMatrix', 'SparseMatrix'];
export var createIdentity = /* #__PURE__ */factory(name, dependencies, function (_ref) {
  var typed = _ref.typed,
      config = _ref.config,
      matrix = _ref.matrix,
      BigNumber = _ref.BigNumber,
      DenseMatrix = _ref.DenseMatrix,
      SparseMatrix = _ref.SparseMatrix;

  /**
   * Create a 2-dimensional identity matrix with size m x n or n x n.
   * The matrix has ones on the diagonal and zeros elsewhere.
   *
   * Syntax:
   *
   *    math.identity(n)
   *    math.identity(n, format)
   *    math.identity(m, n)
   *    math.identity(m, n, format)
   *    math.identity([m, n])
   *    math.identity([m, n], format)
   *
   * Examples:
   *
   *    math.identity(3)                    // returns [[1, 0, 0], [0, 1, 0], [0, 0, 1]]
   *    math.identity(3, 2)                 // returns [[1, 0], [0, 1], [0, 0]]
   *
   *    const A = [[1, 2, 3], [4, 5, 6]]
   *    math.identity(math.size(A))         // returns [[1, 0, 0], [0, 1, 0]]
   *
   * See also:
   *
   *    diag, ones, zeros, size, range
   *
   * @param {...number | Matrix | Array} size   The size for the matrix
   * @param {string} [format]                   The Matrix storage format
   *
   * @return {Matrix | Array | number} A matrix with ones on the diagonal.
   */
  return typed(name, {
    '': function _() {
      return config.matrix === 'Matrix' ? matrix([]) : [];
    },
    string: function string(format) {
      return matrix(format);
    },
    'number | BigNumber': function numberBigNumber(rows) {
      return _identity(rows, rows, config.matrix === 'Matrix' ? 'dense' : undefined);
    },
    'number | BigNumber, string': function numberBigNumberString(rows, format) {
      return _identity(rows, rows, format);
    },
    'number | BigNumber, number | BigNumber': function numberBigNumberNumberBigNumber(rows, cols) {
      return _identity(rows, cols, config.matrix === 'Matrix' ? 'dense' : undefined);
    },
    'number | BigNumber, number | BigNumber, string': function numberBigNumberNumberBigNumberString(rows, cols, format) {
      return _identity(rows, cols, format);
    },
    Array: function Array(size) {
      return _identityVector(size);
    },
    'Array, string': function ArrayString(size, format) {
      return _identityVector(size, format);
    },
    Matrix: function Matrix(size) {
      return _identityVector(size.valueOf(), size.storage());
    },
    'Matrix, string': function MatrixString(size, format) {
      return _identityVector(size.valueOf(), format);
    }
  });

  function _identityVector(size, format) {
    switch (size.length) {
      case 0:
        return format ? matrix(format) : [];

      case 1:
        return _identity(size[0], size[0], format);

      case 2:
        return _identity(size[0], size[1], format);

      default:
        throw new Error('Vector containing two values expected');
    }
  }
  /**
   * Create an identity matrix
   * @param {number | BigNumber} rows
   * @param {number | BigNumber} cols
   * @param {string} [format]
   * @returns {Matrix}
   * @private
   */


  function _identity(rows, cols, format) {
    // BigNumber constructor with the right precision
    var Big = isBigNumber(rows) || isBigNumber(cols) ? BigNumber : null;
    if (isBigNumber(rows)) rows = rows.toNumber();
    if (isBigNumber(cols)) cols = cols.toNumber();

    if (!isInteger(rows) || rows < 1) {
      throw new Error('Parameters in function identity must be positive integers');
    }

    if (!isInteger(cols) || cols < 1) {
      throw new Error('Parameters in function identity must be positive integers');
    }

    var one = Big ? new BigNumber(1) : 1;
    var defaultValue = Big ? new Big(0) : 0;
    var size = [rows, cols]; // check we need to return a matrix

    if (format) {
      // create diagonal matrix (use optimized implementation for storage format)
      if (format === 'sparse') {
        return SparseMatrix.diagonal(size, one, 0, defaultValue);
      }

      if (format === 'dense') {
        return DenseMatrix.diagonal(size, one, 0, defaultValue);
      }

      throw new TypeError("Unknown matrix type \"".concat(format, "\""));
    } // create and resize array


    var res = resize([], size, defaultValue); // fill in ones on the diagonal

    var minimum = rows < cols ? rows : cols; // fill diagonal

    for (var d = 0; d < minimum; d++) {
      res[d][d] = one;
    }

    return res;
  }
});