simplicial-complex - npm Package Compare versions

Comparing version 0.1.1 to 0.2.0

package.json

 {
   "name": "simplicial-complex",
-  "version": "0.1.1",
+  "version": "0.2.0",
   "description": "Topological indexing for simplicial complexes",
@@ -5,0 +5,0 @@ "main": "topology.js",

README.md

@@ -192,9 +192,8 @@ simplicial-complex
 
-### `boundary(cells, n)`
-Computes the <a href="http://en.wikipedia.org/wiki/Boundary_(topology)">d-dimensional boundary</a> of a cell complex.  For example, in a triangular mesh `boundary(tris, 1)` gives an array of all the boundary edges of the mesh; or `boundary(tets, 2)` gives an array of all boundary faces.  Algebraically, this is the same as evaluating the boundary operator in the Z/2 homology.
+### `boundary(cells)`
+Computes the <a href="http://en.wikipedia.org/wiki/Boundary_(topology)">d-dimensional boundary</a> of all cells, including duplicates.
 
 * `cells` is a cell complex.
-* `n` is the dimension of the boundary we are computing.
 
-**Returns:** A `normalize`d array of `n`-dimensional cells representing the boundary of the cell complex.
+**Returns:** An array of cells representing the boundary of the cell complex.
 
@@ -201,0 +200,0 @@ **Time complexity:** `O((d^n + log(cells.length)) * cells.length)`

test/test.js

@@ -224,4 +224,3 @@ var test = require("tap").test
   var tetra = [[0,1,2,3]];
-  arr_equals(t,top.boundary(tetra,2), tris);
-  arr_equals(t,top.boundary(tris,1), []);
+  arr_equals(t,top.normalize(top.boundary(tetra,2)), tris);
   
@@ -228,0 +227,0 @@ t.end();

topology.js

@@ -52,23 +52,21 @@ "use strict"; "use restrict";
     case 2:
-      t = ((a[0]+a[1])&0xffffffff) - ((b[0]+b[1])&0xffffffff);
-      if(t) {
-        return t;
+      var d = a[0]+a[1]-b[0]-b[1];
+      if(d) {
+        return d;
       }
-      return ((a[0]*a[1])&0xffffffff) - ((b[0]*b[1])&0xffffffff);
+      return Math.min(a[0],a[1]) - Math.min(b[0],b[1]);
     case 3:
-      var l0 = (a[0]+a[1])&0xffffffff
-        , l2 = a[2]
-        , m0 = (b[0]+b[1])&0xffffffff
-        , m2 = b[2];
-      t = ((l2+l0)&0xffffffff) - ((m2+m0)&0xffffffff);
-      if(t) {
-        return t;
+      var l1 = a[0]+a[1]
+        , m1 = b[0]+b[1];
+      d = l1+a[2] - (m1+b[2]);
+      if(d) {
+        return d;
       }
-      var l1 = (a[0]*a[1])&0xffffffff
-        , m1 = (b[0]*b[1])&0xffffffff;
-      t = ((l2*l1)&0xffffffff) - ((m2*m1)&0xffffffff);
-      if(t) {
-        return t;
+      var l0 = Math.min(a[0], a[1])
+        , m0 = Math.min(b[0], b[1])
+        , d  = Math.min(l0, a[2]) - Math.min(m0, b[2]);
+      if(d) {
+        return d;
       }
-      return (((l2*l0)&0xffffffff)+l1) - (((m2*m0)&0xffffffff)+m1);
+      return Math.min(l0+a[2], l1) - Math.min(m0+b[2], m1);
       
@@ -110,5 +108,6 @@ //TODO: Maybe optimize n=4 as well?
     return cells
+  } else {
+    cells.sort(compareCells);
+    return cells;
   }
-  cells.sort(compareCells);
-  return cells;
 }
@@ -191,3 +190,3 @@ exports.normalize = normalize;
 //Enumerates all of the n-cells of a cell complex (in more technical terms, the boundary operator with free coefficients)
-function subcells(cells, n) {
+function fullSkeleton(cells, n) {
   if(n < 0) {
@@ -213,3 +212,3 @@ return [];
 }
-exports.subcells = subcells;
+exports.fullSkeleton = fullSkeleton;
 
@@ -221,3 +220,3 @@ //Computes the n-skeleton of a cell complex (in other words, the n-boundary operator in the homology over the Boolean semiring)
   }
-  var res = subcells(cells, n);
+  var res = fullSkeleton(cells, n);
   normalize(res);
@@ -244,25 +243,17 @@ var ptr = 1;
 
-//Computes the nth boundary operator
-function boundary(cells, n) {
-  if(n < 0) {
-    return [];
-  }
-  var res = subcells(cells, n);
-  res.sort(compareCells);
-  var ptr = 0
-    , i   = 0;
-  while(true) {
-    while(i < res.length-1 && compareCells(res[i], res[i+1]) === 0) {
-      i += 2;
+//Computes the boundary of all cells, does not remove duplicates
+function boundary(cells) {
+  var res = [];
+  for(var i=0; i<cells.length; ++i) {
+    var c = cells[i];
+    for(var j=0; j<c.length; ++j) {
+      var b = new Array(c.length-1);
+      for(var k=0, l=0; k<c.length; ++k) {
+        if(k !== j) {
+          b[l++] = c[k];
+        }
+      }
+      res.push(b);
     }
-    if(i >= res.length) {
-      break;
-    }
-    var a = res[ptr++]
-      , b = res[i++];
-    for(var j=0; j<=n; ++j) {
-      a[j] = b[j];
-    }
   }
-  res.length = ptr;
   return res;
@@ -269,0 +260,0 @@ }

No alert changes

Worsened metrics

Total package byte prevSize

22452

decreased by-2.4%

Lines of code

494

decreased by-1.98%

Number of lines in readme file

218

decreased by-0.46%

No dependency changes