mathjs/src/function/algebra/sparse/csIpvec.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 () {
  /**
   * Permutes a vector; x = P'b. In MATLAB notation, x(p)=b.
   *
   * @param {Array} p           The permutation vector of length n. null value denotes identity
   * @param {Array} b           The input vector
   *
   * @return {Array}            The output vector x = P'b
   */
  function csIpvec (p, b) {
    // vars
    let k
    const n = b.length
    const x = []
    // check permutation vector was provided, p = null denotes identity
    if (p) {
      // loop vector
      for (k = 0; k < n; k++) {
        // apply permutation
        x[p[k]] = b[k]
      }
    } else {
      // loop vector
      for (k = 0; k < n; k++) {
        // x[i] = b[i]
        x[k] = b[k]
      }
    }
    return x
  }

  return csIpvec
}

exports.name = 'csIpvec'
exports.path = 'algebra.sparse'
exports.factory = factory