Elements of homogeneous matrices are not initialized when using 2D systems

[omgm]

This issue was found thanks to performing mutation analysis with Mutator (http://ortask.com/mutator/) on test suite homog-test.js.

The constructor for Homog (homog.js) seems to support 2D systems by accepting a 2D rotation matrix and 2D vector as parameters. However, the resulting matrix is not initialized properly.

In particular, I added the following test to homog-test.js as suggested by mutation analysis:

  it('creates matrix with good values for 2D systems', function () {
    var Rz = new Matrix(2, 2);
    var Trans = new Vector(0,0)
    var H1 = new Homog(Rz, Trans);
    H1.m.should.eql([[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 1, 0], [0, 0, 0, 1]]);
  });

but get the following error when running the tests:

  1) Create a homogenous matrix creates matrix with good values for 2D systems:

      AssertionError: expected [ [ 0, 0, , 0 ], [ 0, 0, , 0 ], [ 0, 0, 1, 0 ], [
 0, 0, 0, 1 ] ] to equal [ [ 0, 0, 0, 0 ], [ 0, 0, 0, 0 ], [ 0, 0, 1, 0 ], [ 0,
0, 0, 1 ] ]
      + expected - actual

       [
         [
           0
           0
      -    null
           0
      +    0
         ]
         [
           0
           0
      -    null
           0
      +    0
         ]
         [
           0
           0

Inspecting the constructor for Homog, it seems that the following loop only sets the first four elements of the matrix (as that is the limit when passing in a 2x2 rotation matrix), but leaves elements (0,2) and (1,2) uninitialized (i.e. as null):

  // fill in the rotation part
  for (var r = 0; r < rot.rows; ++r) {
    for (var c = 0; c < rot.cols; ++c) {
      H.set(r, c, rot.get(r, c));
    }
  }