The following Qr decomposition case appears to fail: ``` [[ 0 , 0 ], [ -1 , 0 ]] ``` with results ``` Q= [[ 0.0, 1.0 ], [ 1.0, 0.0 ]] R= [[ -1.0, 0.0 ], [ 0.0, -1.0 ]] ```