diff --git a/web/app/constr/solver.js b/web/app/constr/solver.js
index ef74a982..e7cd8f27 100644
--- a/web/app/constr/solver.js
+++ b/web/app/constr/solver.js
@@ -207,6 +207,15 @@ TCAD.parametric.lock2Equals2 = function(constrs, locked) {
 
 TCAD.parametric._alg = 5;
 
+TCAD.parametric.diagnose = function(sys) {
+  var jacobian = sys.makeJacobian();
+  var qr = new TCAD.math.QR(jacobian);
+  return {
+    conflict : sys.constraints.length > qr.rank,
+    dof : sys.params.length - qr.rank
+  }
+};
+
 TCAD.parametric.prepare = function(constrs, locked, aux, alg) {
 
   this.lock1(constrs, aux);
@@ -234,10 +243,15 @@ TCAD.parametric.prepare = function(constrs, locked, aux, alg) {
     return sys.makeJacobian();
   };
   alg = TCAD.parametric._alg;
+  var _point = [];
   
   function solve(fineLevel) {
     if (constrs.length == 0) return;
     if (sys.params.length == 0) return;
+    if (TCAD.parametric.diagnose(sys).conflict) {
+      console.log("Conflicting or redundant constraints. Please fix your system.");
+      return;
+    }
     if (alg > 0) {
       switch (alg) {
         case 1:
@@ -255,8 +269,8 @@ TCAD.parametric.prepare = function(constrs, locked, aux, alg) {
           break;
         case 5:
           if (optim.dog_leg(sys) !== 0) {
-            alg = -5;
-            solve(fineLevel);
+            //alg = -5;
+            //solve(fineLevel);
           }
           break;
       }
diff --git a/web/app/math/qr.js b/web/app/math/qr.js
index 9f51b555..cd940f29 100644
--- a/web/app/math/qr.js
+++ b/web/app/math/qr.js
@@ -1,24 +1,33 @@
-TCAD.math.qr = function(matrix) {
 
-  function arr(size) {
-    var out = [];
-    out.length = size;
-    for (var i = 0; i < size; ++i) {
-      out[i] = 0;
-    }
-    return out;
+TCAD.math.vec = function(size) {
+  var out = [];
+  out.length = size;
+  for (var i = 0; i < size; ++i) {
+    out[i] = 0;
   }
+  return out;
+};
+
+
+TCAD.math.Arrays_fill = function(a, fromIndex, toIndex,val) {
+  for (var i = fromIndex; i < toIndex; i++)
+    a[i] = val;
+};
+
+TCAD.math.QR = function(matrix) {
+  var vec = TCAD.math.vec;
+  this.matrix = matrix;
+  var nR = this.matrix.length;
+  var nC = this.matrix[0].length;
 
   this.qrRankingThreshold = 1e-30; //??
   this.solvedCols  = Math.min(nR, nC);
-  this.diagR     = arr(nC);
-  this.norm    = arr(nC);
-  this.beta    = arr(nC);
-  this.permutation = arr(nC);
+  this.diagR     = vec(nC);
+  this.norm    = vec(nC);
+  this.beta    = vec(nC);
+  this.permutation = vec(nC);
   this.rank = null;
 
-  var nR = this.matrix.length;
-  var nC = this.matrix[0].length;
   var k;
   var norm2;
   var akk;
@@ -88,3 +97,131 @@ TCAD.math.qr = function(matrix) {
   }
   this.rank = this.solvedCols;
 };
+
+TCAD.math.QR.prototype.qTy = function(y) {
+  var nR = this.matrix.length;
+  var nC = this.matrix[0].length;
+
+  for (var k = 0; k < nC; ++k) {
+    var pk = this.permutation[k];
+    var gamma = 0;
+    for (var i = k; i < nR; ++i) {
+      gamma += this.matrix[i][pk] * y[i];
+    }
+    gamma *= this.beta[pk];
+    for (var i = k; i < nR; ++i) {
+      y[i] -= gamma * this.matrix[i][pk];
+    }
+  }
+};
+
+TCAD.math.QR.prototype.solve = function(qy) {
+
+  var nR = this.matrix.length;
+  var nC = this.matrix[0].length;
+
+  var vec = TCAD.math.vec;
+  
+  var diag = vec(nC);
+  var lmDiag = vec(nC);
+  var work = vec(nC);
+  var out =  vec(nC);
+  
+  // copy R and Qty to preserve input and initialize s
+  //  in particular, save the diagonal elements of R in lmDir
+  for (var j = 0; j < this.solvedCols; ++j) {
+    var pj = this.permutation[j];
+    for (var i = j + 1; i < this.solvedCols; ++i) {
+      this.matrix[i][pj] = this.matrix[j][this.permutation[i]];
+    }
+    out[j] = this.diagR[pj];
+    work[j]  = qy[j];
+  }
+
+  // eliminate the diagonal matrix d using a Givens rotation
+  for (var j = 0; j < this.solvedCols; ++j) {
+
+    // prepare the row of d to be eliminated, locating the
+    // diagonal element using p from the Q.R. factorization
+    var pj = this.permutation[j];
+    var dpj = diag[pj];
+    if (dpj != 0) {
+      TCAD.math.Arrays_fill(lmDiag, j + 1, lmDiag.length, 0);
+    }
+    lmDiag[j] = dpj;
+
+    //  the transformations to eliminate the row of d
+    // modify only a single element of Qty
+    // beyond the first n, which is initially zero.
+    var qtbpj = 0;
+    for (var k = j; k < this.solvedCols; ++k) {
+      var pk = this.permutation[k];
+
+      // determine a Givens rotation which eliminates the
+      // appropriate element in the current row of d
+      if (lmDiag[k] != 0) {
+
+        var sin;
+        var cos;
+        var rkk = this.matrix[k][pk];
+        if (Math.abs(rkk) < Math.abs(lmDiag[k])) {
+          var cotan = rkk / lmDiag[k];
+          sin   = 1.0 / Math.sqrt(1.0 + cotan * cotan);
+          cos   = sin * cotan;
+        } else {
+          var tan = lmDiag[k] / rkk;
+          cos = 1.0 / Math.sqrt(1.0 + tan * tan);
+          sin = cos * tan;
+        }
+
+        // compute the modified diagonal element of R and
+        // the modified element of (Qty,0)
+        this.matrix[k][pk] = cos * rkk + sin * lmDiag[k];
+        var temp = cos * work[k] + sin * qtbpj;
+        qtbpj = -sin * work[k] + cos * qtbpj;
+        work[k] = temp;
+
+        // accumulate the tranformation in the row of s
+        for (var i = k + 1; i < this.solvedCols; ++i) {
+          var rik = this.matrix[i][pk];
+          var temp2 = cos * rik + sin * lmDiag[i];
+          lmDiag[i] = -sin * rik + cos * lmDiag[i];
+          this.matrix[i][pk] = temp2;
+        }
+      }
+    }
+
+    // store the diagonal element of s and restore
+    // the corresponding diagonal element of R
+    lmDiag[j] = this.matrix[j][this.permutation[j]];
+    this.matrix[j][this.permutation[j]] = out[j];
+  }
+
+  // solve the triangular system for z, if the system is
+  // singular, then obtain a least squares solution
+  var nSing = this.solvedCols;
+  for (var j = 0; j < this.solvedCols; ++j) {
+    if ((lmDiag[j] == 0) && (nSing == this.solvedCols)) {
+      nSing = j;
+    }
+    if (nSing < this.solvedCols) {
+      work[j] = 0;
+    }
+  }
+  if (nSing > 0) {
+    for (var j = nSing - 1; j >= 0; --j) {
+      var pj = this.permutation[j];
+      var sum = 0;
+      for (var i = j + 1; i < nSing; ++i) {
+        sum += this.matrix[i][pj] * work[i];
+      }
+      work[j] = (work[j] - sum) / lmDiag[j];
+    }
+  }
+
+  // permute the components of z back to components of lmDir
+  for (var j = 0; j < out.length; ++j) {
+    out[this.permutation[j]] = work[j];
+  }
+  return out;
+};
\ No newline at end of file
diff --git a/web/app/math/test.js b/web/app/math/test.js
index d025fe89..57e90b01 100644
--- a/web/app/math/test.js
+++ b/web/app/math/test.js
@@ -55,13 +55,19 @@ function testCompare() {
 
 function lsolve() {
   var n = numeric;
-  A = [[1, 0, 0], [2,3,0]]
-  b = [10,25]
+  var A = [[2,3], [1,1]];
+  var b = [13,5];
 //  var At = n.transpose(A);
 //  var A = n.dot(At, A);
 //  var b = n.dot(At, b);
 //  var res = n.dot(n.dot(At, n.inv(n.dot(A, At)) ), b);
-  var res = optim.cg(A, [100, 100, 0], b, 1e-8, 800);
+//  var res = optim.cg(A, [100, 100, 0], b, 1e-8, 800);
+  
+  //var qr = new TCAD.math.QR(A);
+  //qr.qTy(b);
+  //var res = qr.solve(b);
+
+  var res = n.solve(A, b);
   console.log(res);
 }
 
diff --git a/web/sketcher.html b/web/sketcher.html
index 791aa5a4..9717e0d7 100644
--- a/web/sketcher.html
+++ b/web/sketcher.html
@@ -192,6 +192,7 @@
 
   <script src="app/vector.js"></script>
   <script src="app/math/math.js"></script>
+  <script src="app/math/qr.js"></script>
   <script src="app/math/matrix.js"></script>
   <script src="app/math/optim.js"></script>
   <script src="app/math/noptim.js"></script>
diff --git a/web/test.html b/web/test.html
index 36caa05e..a92ead56 100644
--- a/web/test.html
+++ b/web/test.html
@@ -1,27 +1,44 @@
 <html>
 <head>
-	<title>Test Suite</title>
+	<title>TCAD</title>
+	<style>
+		body {
+			font-family: Monospace;
+			margin: 0px;
+			overflow: hidden;
+		}
+	</style>
 
+	<script> TCAD = {} </script>
+	
 	<script src="lib/three/three.js"></script>
-	<script src="lib/three/TrackballControls.js"></script>
-	<script src="lib/three/OrbitControls.js"></script>
-	<script src="lib/dat.gui.min.js"></script>
-	<script src="lib/csg.js"></script>
-	<script src="lib/pnltri.js"></script>
-	<script src="app/main.js"></script>
-	<script src="app/ctrl.js"></script>
-	<script src="app/viewer.js"></script>
-	<script src="app/engine.js"></script>
+	<script src="lib/numeric-1.2.6.js"></script>
+	<script src="app/canvas.js"></script>
 	<script src="app/vector.js"></script>
 	<script src="app/math/math.js"></script>
-	<script src="app/workbench.js"></script>
-	<script src="app/math/graph.js"></script>
-	<script src="app/struct.js"></script>
-	<script src="app/struct-tests.js"></script>
+	<script src="app/math/qr.js"></script>
+	<script src="app/engine.js"></script>
+	
+	<script src="app/math/matrix.js"></script>
+	<script src="app/math/optim.js"></script>
+	<script src="app/math/noptim.js"></script>
 
-	<script>window.onload = function() {
-		TCAD.struct.tests.testHashTable();
-	}</script>
+	<script src="app/math/lm.js"></script>
+	<script src="app/constr/constraints.js"></script>
+	<script src="app/constr/solver.js"></script>
+
+	<script src="app/engine.js"></script>
+	<script src="app/math/test.js"></script>
+
+	<script>
+		function start() {
+			new TCAD.App2D();
+		}
+		window.onload = function() {
+//			testCompare();
+			lsolve();
+		}
+	</script>
 </head>
 <body>