Bug#702461: atlas: dot or eigenvalue rounding issues on i386

[Julian Taylor]

Package: atlas
Version: 3.8.4-9
Severity: normal

atlas seems to have pretty severe rounding issues on i386 dot products
or eigenvalues
a scipy test fails with atlas but not with netlib blas or openblas
amd64 is not affected:

update-alternatives --set libblas.so.3
/usr/lib/openblas-base/libopenblas.so.0
python /usr/lib/python2.7/dist-packages/scipy/linalg/tests/test_decomp.py
#works fine except for a known failure

update-alternatives --set libblas.so.3
/usr/lib/atlas-base/atlas/libblas.so.3

python /usr/lib/python2.7/dist-packages/scipy/linalg/tests/test_decomp.py


Arrays are not almost equal to 6 decimals

array([[22, 34, 31, 31, 17],
       [45, 45, 42, 19, 29],
       [39, 47, 49, 26, 34],
       [27, 31, 26, 21, 15],
       [38, 44, 44, 24, 30]])
array([[13, 26, 25, 17, 24],
       [31, 46, 40, 26, 37],
       [26, 40, 19, 25, 25],
       [16, 25, 27, 14, 23],
       [24, 35, 18, 21, 22]])
(mismatch 25.0%)
 x: array([ -3.63672429e-01 +0.00000000e+00j,
        -1.72783306e-15 -3.75494248e-08j,
        -1.72783306e-15 +3.75494248e-08j,   2.00000000e+00
+0.00000000e+00j])
 y: array([ -5.22147673e-01 +0.00000000e+00j,
         2.32897931e-16 -2.61904476e-08j,
         2.32897931e-16 +2.61904476e-08j,   2.00000000e+00
+0.00000000e+00j])