For example, here's Y: Y =
-0.278098 -0.256438 0.127559 -0.045869 -0.769172 -0.255599 0.150450 -0.436548 0.209881 -0.526238 0.613175 -0.600739 -0.291662 -1.142282 0.277204 -0.296846 -0.175122 0.031656 -0.202138 -0.254480 -0.187816 -0.889571 0.052191 -0.304053 0.498097 -0.049822 -0.972282 -0.240532 0.155711 -0.627668 -0.065179 -0.055424 0.977480 0.104342 0.594501 0.033205 -0.896222 -0.345715 -0.371288 -0.489602 -0.434807 -0.403650 0.264583 -0.110285 -1.318951 -0.452470 0.274445 -0.755704 0.313150 -0.903234 and R from the QR decomposition of Y' * Y: R = 2.56259 -1.35164 -2.43837 1.27844 -0.17692 -0.30514 1.09366 -0.84664 0.58601 1.06875 0.00000 1.03316 2.61600 -0.46070 -1.46785 -0.10841 0.24828 -2.32186 -2.00163 -0.71470 0.00000 0.00000 2.11507 1.15523 1.10757 0.36407 -0.31567 2.77361 0.77367 -0.84055 0.00000 0.00000 0.00000 0.54242 -0.01545 0.21761 0.26630 0.13972 0.44089 0.02783 0.00000 0.00000 0.00000 0.00000 0.00000 -0.00000 -0.00000 0.00000 0.00000 -0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 -0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 -0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 -0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Separately I tried avoiding the inverse altogether here and just using the QR decomposition to solve a system where necessary. Probably a better move anyway. But same result. I think I'm not really quantifying the problem properly, but it's not really a matter of condition number or machine precision. Condition numbers are >1 in these cases but not that large. On Sun, Apr 7, 2013 at 12:19 AM, Koobas <[email protected]> wrote: > I don't see why the inverse of Y'*Y does not exist. > What Y do you end up with?
