Describe the issue:

I thought i was going mad about a 2D gradient calculation, so I made a simple check: a 2D gaussian should have all arrows pointing towards the peak. But that is not what I observe when plotting a quiver diagram, it looks more like the center being a hyperbolic point.

Reproduce the code example:

import numpy as np
import matplotlib.pyplot as plt

def gaussian_2d(x, y):
    return np.exp(-(x**2 + y**2) / 2)

x = np.linspace(-5, 5, 20)
y = np.linspace(-5, 5, 20)

X, Y = np.meshgrid(x, y)
Z = gaussian_2d(X, Y)

grad_x, grad_y = np.gradient(Z)

plt.figure(figsize=(8, 8))
plt.quiver(X, Y, grad_x, grad_y, color='b')
plt.xlabel('x')
plt.ylabel('y')
plt.show()

Error message:

Python and NumPy Versions:

Python 3.9.21
Numpy 2.0.2

Runtime Environment:

[{'numpy_version': '2.0.2',
'python': '3.9.21 (main, Feb 10 2025, 00:00:00) \n'
'[GCC 11.5.0 20240719 (Red Hat 11.5.0-5)]',
'uname': uname_result(system='Linux', node='XXX', release='5.14.0-578.el9.x86_64', version='#1 SMP PREEMPT_DYNAMIC Mon Apr 7 19:22:46 UTC 2025', machine='x86_64')},
{'simd_extensions': {'baseline': ['SSE', 'SSE2', 'SSE3'],
'found': ['SSSE3',
'SSE41',
'POPCNT',
'SSE42',
'AVX',
'F16C',
'FMA3',
'AVX2',
'AVX512F',
'AVX512CD',
'AVX512_SKX',
'AVX512_CLX'],
'not_found': ['AVX512_KNL',
'AVX512_KNM',
'AVX512_CNL',
'AVX512_ICL']}},
{'architecture': 'SkylakeX',
'filepath': '/home/XXX/myenv/lib/python3.9/site-packages/numpy.libs/libscipy_openblas64_-99b71e71.so',
'internal_api': 'openblas',
'num_threads': 64,
'prefix': 'libscipy_openblas',
'threading_layer': 'pthreads',
'user_api': 'blas',
'version': '0.3.27'},
{'architecture': 'SkylakeX',
'filepath': '/home/XXX/myenv/lib/python3.9/site-packages/scipy.libs/libopenblasp-r0-01191904.3.27.so',
'internal_api': 'openblas',
'num_threads': 64,
'prefix': 'libopenblas',
'threading_layer': 'pthreads',
'user_api': 'blas',
'version': '0.3.27'}]

Context for the issue:

If this turns out to be a bug (and given how simple the reference code is i doubt I made a mistake) this is quite important, since gradients are all over the place.