svdJs is broken, qrJs too, probably from identSize

[xionluhnis]

See NaturalNode/node-lapack#2

Using the following on matlab / octave:

A = [ 1, 2; 3, 4; 5, 6];
[u, s, v] = svd(A)

I obtain:

u =
  -0.22985   0.88346   0.40825
  -0.52474   0.24078  -0.81650
  -0.81964  -0.40190   0.40825

  s =
  9.52552  0.00000
  0.00000  0.51430
  0.00000  0.00000

  v =
  -0.61963  -0.78489
  -0.78489   0.61963

Now with the js implementation:

require('sylvester');
var A = $M([
  [1, 2],
  [3, 4],
  [5, 6]
]);
var svd = A.svd();
console.log(JSON.stringify(svd));

I obtain nothing because it crashes:

  /[...]/node_modules/sylvester/lib/node-sylvester
  /matrix.js:60
    var e = S.triu(1).unroll().norm();
              ^
  TypeError: Cannot call method 'triu' of null
    at Object.svdJs (/[...]/node_modules/sylvester
  /lib/node-sylvester/matrix.js:60:15)

Error summary: it breaks because of a null value being returned by qrJs, which in turn starts with the R matrix being null at some point. That comes from identSize.

However, it's mostly just an issue notification. I personally needed to have reliable and fast svd, so I used SVDLIBC and bound it as a C++ module (see node-svd). You may look at SVDLIBC if you think it can help you with svd / qr processing.