Numpy crashes when I try to find the inverse of a square matrix. On the other hand, when I try to solve a linear least-squares problem, it does not obtain the correct answer.

1) Go to the Python interactor.
2) Enter the following commands:
import numpy
B = numpy.array([[1,2],[3,4]])
numpy.linalg.inv(B)

Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/home/user/Documents/Mis_Programas/Slicer-4.1.0-linux-amd64/lib/Python/lib/python2.6/site-packages/numpy/linalg/linalg.py", line 423, in inv
return wrap(solve(a, identity(a.shape[0], dtype=a.dtype)))
File "/home/user/Documents/Mis_Programas/Slicer-4.1.0-linux-amd64/lib/Python/lib/python2.6/site-packages/numpy/linalg/linalg.py", line 310, in solve
return wrap(b.transpose().astype(result_t))
ValueError: On entry to DGESV parameter number 4 had an illegal value

I tried the same in the system installed python, and the answer is this one:

array([[-2. , 1. ],
[ 1.5, -0.5]])

Solving a linear least-squares problem:

Once again, in the Python Interactor:

1) Import the numpy package (in case you haven't imported it yet)
import numpy
2) Enter the following commands:
x = numpy.array([0, 1, 2, 3])
y = numpy.array([-1, 0.2, 0.9, 2.1])
A = numpy.vstack([x, numpy.ones(len(x))]).T
numpy.linalg.lstsq(A, y)
(array([-1. , 0.2]), array([], dtype=float64), 0, array([ 0., 0.]))

This is not the correct answer!!

I tried the same in the system installed python, and the correct answer is obtained:

(array([ 1. , -0.95]), array([ 0.05]), 2, array([ 4.10003045, 1.09075677]))