Closed
Description
I am getting randomly corrupted results from np.dot if the first argument is an array of doubles with FORTRAN layout.
The behavior is non-deterministic and the does not occur unless I import a large module beforehand (e.g. seaborn or theano does the trick).
Reproducing code example:
import numpy as np
random = dict(
int = lambda shape: np.random.randint(low=0, high=10, size=shape),
float = lambda shape: np.random.randn(*shape)
)
def check_dot(A, b, attempts=10, eps=1e-1):
expected = (A * b).sum(axis=1)
for i in range(attempts):
actual = np.dot(A, b)
if not np.allclose(expected, actual, eps):
return False
return True
def test(n_cols=2):
for n_rows in 2**np.arange(1, 16, 1):
for type, f in random.items():
A = f((n_rows, n_cols))
b = f((n_cols,))
for order in 'CF':
Ac = np.copy(A, order=order)
if not check_dot(Ac, b):
print(type, n_rows, order)
return Ac, b
return None
assert test() is None
import seaborn # or import theano
Ac, b = test()prints
float 8192 F
The error reliably occurs for matrices of larger sizes.
Examples of corrupted results (random data)
If the failure occurs and I evaluate np.dot(Ac, b) a few times
import matplotlib.pyplot as plt
n_eval = 4
f, axes = plt.subplots(n_eval, 1, True, True, figsize=(8, 1.5*n_eval))
expected = (Ac*b).sum(axis=1)
for ax in axes:
actual = np.dot(Ac, b)
ax.plot(actual - expected)
the output is non-deterministic and the errors look like this:
Examples of corrupted results (structured data)
If I replace the normal random generator with linspace:
random = dict(
int = lambda shape: np.random.randint(low=0, high=10, size=shape),
float = lambda shape: np.linspace(0, 1, np.product(shape)).reshape(shape)
)I get errors plots looking like this:
Numpy/Python version information:
Since I am using numpy packaged for nix package manager it is easy to get exactly the same Python environment package on a different machine. I did not do this yet.
>> sys.version
3.6.6 (default, Jun 27 2018, 05:47:41)
[GCC 7.3.0]
>> np.__version__
1.15.1
>> np.show_config()
blas_mkl_info:
NOT AVAILABLE
blis_info:
NOT AVAILABLE
openblas_info:
libraries = ['openblas', 'openblas']
library_dirs = ['/nix/store/blk28p4cr6r2nc7fi1c4gggiqpd7pkqy-openblas-0.3.1/lib']
language = c
define_macros = [('HAVE_CBLAS', None)]
blas_opt_info:
libraries = ['openblas', 'openblas']
library_dirs = ['/nix/store/blk28p4cr6r2nc7fi1c4gggiqpd7pkqy-openblas-0.3.1/lib']
language = c
define_macros = [('HAVE_CBLAS', None)]
lapack_mkl_info:
NOT AVAILABLE
openblas_lapack_info:
libraries = ['openblas', 'openblas']
library_dirs = ['/nix/store/blk28p4cr6r2nc7fi1c4gggiqpd7pkqy-openblas-0.3.1/lib']
language = c
define_macros = [('HAVE_CBLAS', None)]
lapack_opt_info:
libraries = ['openblas', 'openblas']
library_dirs = ['/nix/store/blk28p4cr6r2nc7fi1c4gggiqpd7pkqy-openblas-0.3.1/lib']
language = c
define_macros = [('HAVE_CBLAS', None)]