feat:node-modules

node_modules/mathjs/lib/esm/function/algebra/sparse/csReach.js

@@ -0,0 +1,52 @@
+// Copyright (c) 2006-2024, Timothy A. Davis, All Rights Reserved.
+// SPDX-License-Identifier: LGPL-2.1+
+// https://github.com/DrTimothyAldenDavis/SuiteSparse/tree/dev/CSparse/Source
+
+import { csMarked } from './csMarked.js';
+import { csMark } from './csMark.js';
+import { csDfs } from './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
+ */
+export 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 (!csMarked(gptr, i)) {
+      // start a dfs at unmarked node i
+      top = csDfs(i, g, top, xi, pinv);
+    }
+  }
+  // loop columns from top -> n - 1
+  for (p = top; p < n; p++) {
+    // restore G
+    csMark(gptr, xi[p]);
+  }
+  return top;
+}