ysjj-system/node_modules/mathjs/lib/cjs/function/algebra/sparse/csReach.js

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.csReach = csReach;
var _csMarked = require("./csMarked.js");
var _csMark = require("./csMark.js");
var _csDfs = require("./csDfs.js");
/**
 * The csReach function computes X = Reach(B), where B is the nonzero pattern of the n-by-1
 * sparse column of vector b. The function returns the set of nodes reachable from any node in B. The
 * nonzero pattern xi of the solution x to the sparse linear system Lx=b is given by X=Reach(B).
 *
 * @param {Matrix}  g               The G matrix
 * @param {Matrix}  b               The B matrix
 * @param {Number}  k               The kth column in B
 * @param {Array}   xi              The nonzero pattern xi[top] .. xi[n - 1], an array of size = 2 * n
 *                                  The first n entries is the nonzero pattern, the last n entries is the stack
 * @param {Array}   pinv            The inverse row permutation vector
 *
 * @return {Number}                 The index for the nonzero pattern
 *
 * Reference: http://faculty.cse.tamu.edu/davis/publications.html
 */
function csReach(g, b, k, xi, pinv) {
  // g arrays
  var gptr = g._ptr;
  var gsize = g._size;
  // b arrays
  var bindex = b._index;
  var bptr = b._ptr;
  // columns
  var n = gsize[1];
  // vars
  var p, p0, p1;
  // initialize top
  var top = n;
  // loop column indeces in B
  for (p0 = bptr[k], p1 = bptr[k + 1], p = p0; p < p1; p++) {
    // node i
    var i = bindex[p];
    // check node i is marked
    if (!(0, _csMarked.csMarked)(gptr, i)) {
      // start a dfs at unmarked node i
      top = (0, _csDfs.csDfs)(i, g, top, xi, pinv);
    }
  }
  // loop columns from top -> n - 1
  for (p = top; p < n; p++) {
    // restore G
    (0, _csMark.csMark)(gptr, xi[p]);
  }
  return top;
}