below is the answer from Osni Marques:
Dear Buroc,
Please take a look at
http://crd.lbl.gov/~osni/Codes/stetester for results
and the test suite that we have used for LAPACK's tridiagonal
eigensolvers. The tester infrastructure (written in Fortran 90) that we
have used to obtain the results is available upon request (see "technical
report" in the URL given above).
Osni