80 lines
1.7 KiB
JavaScript
80 lines
1.7 KiB
JavaScript
"use strict";
|
|
|
|
Object.defineProperty(exports, "__esModule", {
|
|
value: true
|
|
});
|
|
exports.csEtree = csEtree;
|
|
|
|
/**
|
|
* Computes the elimination tree of Matrix A (using triu(A)) or the
|
|
* elimination tree of A'A without forming A'A.
|
|
*
|
|
* @param {Matrix} a The A Matrix
|
|
* @param {boolean} ata A value of true the function computes the etree of A'A
|
|
*
|
|
* Reference: http://faculty.cse.tamu.edu/davis/publications.html
|
|
*/
|
|
function csEtree(a, ata) {
|
|
// check inputs
|
|
if (!a) {
|
|
return null;
|
|
} // a arrays
|
|
|
|
|
|
var aindex = a._index;
|
|
var aptr = a._ptr;
|
|
var asize = a._size; // rows & columns
|
|
|
|
var m = asize[0];
|
|
var n = asize[1]; // allocate result
|
|
|
|
var parent = []; // (n)
|
|
// allocate workspace
|
|
|
|
var w = []; // (n + (ata ? m : 0))
|
|
|
|
var ancestor = 0; // first n entries in w
|
|
|
|
var prev = n; // last m entries (ata = true)
|
|
|
|
var i, inext; // check we are calculating A'A
|
|
|
|
if (ata) {
|
|
// initialize workspace
|
|
for (i = 0; i < m; i++) {
|
|
w[prev + i] = -1;
|
|
}
|
|
} // loop columns
|
|
|
|
|
|
for (var k = 0; k < n; k++) {
|
|
// node k has no parent yet
|
|
parent[k] = -1; // nor does k have an ancestor
|
|
|
|
w[ancestor + k] = -1; // values in column k
|
|
|
|
for (var p0 = aptr[k], p1 = aptr[k + 1], p = p0; p < p1; p++) {
|
|
// row
|
|
var r = aindex[p]; // node
|
|
|
|
i = ata ? w[prev + r] : r; // traverse from i to k
|
|
|
|
for (; i !== -1 && i < k; i = inext) {
|
|
// inext = ancestor of i
|
|
inext = w[ancestor + i]; // path compression
|
|
|
|
w[ancestor + i] = k; // check no anc., parent is k
|
|
|
|
if (inext === -1) {
|
|
parent[i] = k;
|
|
}
|
|
}
|
|
|
|
if (ata) {
|
|
w[prev + r] = k;
|
|
}
|
|
}
|
|
}
|
|
|
|
return parent;
|
|
} |