#199 xsqrtst_pt fails on ARM when tgeqr2 is called

Developer
closed-fixed
5
2012-03-24
2012-03-12
R. Clint Whaley
No

If you hack METHOD in atlas_qrmeth.h to always do either PCA copy or no copy, and hardwire nb=4 in ATL_geqrf, then N>10 will get the wrong answer. If tgeqr2 is not called, answer is always correct.

Discussion

  • Not sure if it is related, but xsqrtst_pt also fails sanity checks on 32-bit opt8.

     
  • G5 and G4 xsqrtst_pt sporadically fail as well, but this is almost certainly unrelated since it only occasionally happens.

     
    • status: open --> closed-fixed
     
  • Both problems caused by out-of-order writes (ARM and PPC both do this). Problem fixed by turning off PCA for these archs.