Scale FAIL with SPDIAM in xLARRF. Fixes #995.#1309
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martin-frbg
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Jun 15, 2026
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Description
As discussed in #995, a failure to correctly compare the relative error scale
FAILand the absoluteSMLGROWTHled to unexpected failure of xLARFF when the input is scaled well away from 1. This led to eigensolver routines such asZHEEVRrunning up to 20x slower when given input scaled away from 1 by a large factor (e.g. 1e12). Example matrices can be generate with the following code: https://gist.github.com/amilsted/24e77bc77a39dbbcabf718a3ce5b5fe3This fix eliminates the eigensolve slowdown due to xLARFF failure in the tested cases.
Closes #995.