What to do with `NeedPiecewiseCorrection()`?

Is this a reliable test of the R matrix in the QR decomposition having only positive eigenvalues?
If yes, then this method should be renamed (at least to lower case characters) and exported. If no, then it probably should be deleted.

Start by locating the implementation of NeedPiecewiseCorrection() and the QR decomposition code or tests that call it. Determine whether it reliably checks the stated eigenvalue condition, then resolve the issue by documenting the chosen outcome: rename and export the method, or remove it if the check is not reliable.

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