BUG: Failure to create sparse matrix on PPC

This is from https://github.com/conda-forge/osqp-feedstock/pull/39, happens both with openblas & netlib backends. Scipy version 1.7.1, numpy 1.21.1.

Minimal example directly from osqp test suite:

import scipy
from scipy import sparse
scipy.random.seed(1)
sparse.random(5, 5, density=0.7)

fails with

[...]/lib/python3.8/site-packages/osqp/tests/update_matrices_test.py:23:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
[...]/lib/python3.8/site-packages/scipy/sparse/construct.py:813: in random
    return coo_matrix((vals, (i, j)), shape=(m, n)).asformat(format,
[...]/lib/python3.8/site-packages/scipy/sparse/coo.py:196: in __init__
    self._check()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <5x5 sparse matrix of type '<class 'numpy.float64'>'
        with 18 stored elements in COOrdinate format>

    def _check(self):
        """ Checks data structure for consistency """

        # index arrays should have integer data types
        if self.row.dtype.kind != 'i':
            warn("row index array has non-integer dtype (%s)  "
                    % self.row.dtype.name)
        if self.col.dtype.kind != 'i':
            warn("col index array has non-integer dtype (%s) "
                    % self.col.dtype.name)

        idx_dtype = get_index_dtype(maxval=max(self.shape))
        self.row = np.asarray(self.row, dtype=idx_dtype)
        self.col = np.asarray(self.col, dtype=idx_dtype)
        self.data = to_native(self.data)

        if self.nnz > 0:
            if self.row.max() >= self.shape[0]:
>               raise ValueError('row index exceeds matrix dimensions')
E               ValueError: row index exceeds matrix dimensions

Same thing for scipy.sparse.random(100, 200, density=0.9, format='csc'),

[h-vetinari]

Thanks for taking a look!

I’m just packaging the library, it’s not “my” code, which comes from here.

Indeed the import is done separately there; I had just tried to translate that function into a minimal example (without rerunning directly) - apologies.

[rgommers]

Probably an emulation bug, this code is too simple to actually be broken specifically on PPC I’d think. Let’s close it - if someone finds this problem on an actual PPC machine instead of on QEMU please reopen.