[math] Pivoting in QR decomposition

[Greg Sterijevski]

Hello,

In attempting to build constrained ols into the OLSMultipleLinearRegression
class, I rediscovered the fact that to keep the regression coefficients in
their canonical order, I need to know how the QR decomposition pivoted. In
other words, while I get the correct constrained parameters, their order is
changed. Is there any way to get this info out (pivot order)?

Thanks,

-Greg