*drgev: relax eigenvalue consistency test#1297
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The ZGGEV/DGGEV/SGGEV/CGGEV test drivers compared eigenvalues
from full (both L/R eigenvectors) and partial (eigenvalues only)
computations using exact Fortran .NE. This is fragile because the
QZ algorithm applies orthogonal transformations to a different
scope of columns depending on the JOB parameter ('S' vs 'E'),
causing 1-ULP differences in eigenvalues on some architectures.
Replace the binary ULPINV sentinel with a relative tolerance
comparison: RESULT(5/6/7) now reports the maximum relative
difference across ALPHA/ALPHAI/BETA, which is compared against
the regular THRESH threshold. Fixes the spurious failure on
Intel Xeon E5-2698 v4 and other platforms.
Closes Reference-LAPACK#744
martin-frbg
approved these changes
Jun 13, 2026
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The ZGGEV/DGGEV/SGGEV/CGGEV test drivers compared eigenvalues from full (both L/R eigenvectors) and partial (eigenvalues only) computations using exact Fortran .NE. This is fragile because the QZ algorithm applies orthogonal transformations to a different scope of columns depending on the JOB parameter ('S' vs 'E'), causing 1-ULP differences in eigenvalues on some architectures.
Replace the binary ULPINV sentinel with a relative tolerance comparison: RESULT(5/6/7) now reports the maximum relative difference across ALPHA/ALPHAI/BETA, which is compared against the regular THRESH threshold. Fixes the spurious failure on Intel Xeon E5-2698 v4 and other platforms.
Closes #744