ENH: linalg: consistent support for zero-size batch #24148
Description
Describe your issue.
In the 1.17 release candidate, scipy.linalg.toeplitz unexpectedly returns a list rather than array when passed batched input with an empty batch.
Reproducing Code Example
import numpy as np
import scipy
print(f"{scipy.__version__=}")
result = scipy.linalg.toeplitz(np.zeros((0, 4)))
print(type(result), result)Error message
scipy.__version__='1.17.0rc1'
<class 'list'> []The expected output here would be an ndarray with shape (0, 4, 4).
SciPy/NumPy/Python version and system information
1.17.0rc1 2.3.5 sys.version_info(major=3, minor=12, micro=12, releaselevel='final', serial=0)
Build Dependencies:
blas:
detection method: pkgconfig
found: true
has ilp64: false
include directory: /opt/_internal/cpython-3.12.11/lib/python3.12/site-packages/scipy_openblas32/include
lib directory: /opt/_internal/cpython-3.12.11/lib/python3.12/site-packages/scipy_openblas32/lib
name: scipy-openblas
openblas configuration: OpenBLAS 0.3.30 DYNAMIC_ARCH NO_AFFINITY Haswell MAX_THREADS=64
pc file directory: /project/
version: 0.3.30
lapack:
detection method: pkgconfig
found: true
has ilp64: false
include directory: /opt/_internal/cpython-3.12.11/lib/python3.12/site-packages/scipy_openblas32/include
lib directory: /opt/_internal/cpython-3.12.11/lib/python3.12/site-packages/scipy_openblas32/lib
name: scipy-openblas
openblas configuration: OpenBLAS 0.3.30 DYNAMIC_ARCH NO_AFFINITY Haswell MAX_THREADS=64
pc file directory: /project/
version: 0.3.30
pybind11:
detection method: config-tool
include directory: unknown
name: pybind11
version: 3.0.1
Compilers:
c:
commands: cc
linker: ld.bfd
name: gcc
version: 14.2.1
c++:
commands: c++
linker: ld.bfd
name: gcc
version: 14.2.1
cython:
commands: cython
linker: cython
name: cython
version: 3.2.2
fortran:
commands: gfortran
linker: ld.bfd
name: gcc
version: 14.2.1
pythran:
include directory: ../../tmp/build-env-fjeibmbd/lib/python3.12/site-packages/pythran
version: 0.18.1
Machine Information:
build:
cpu: x86_64
endian: little
family: x86_64
system: linux
cross-compiled: false
host:
cpu: x86_64
endian: little
family: x86_64
system: linux
Python Information:
path: /tmp/build-env-fjeibmbd/bin/python
version: '3.12'