Bug in python3-symp and python-sympy 1.3-2

[Andrius Merkys]

Hi Rafel,

On 2020-12-14 20:25, Rafel Amer Ramon wrote:
> if I run the code
> 
> from sympy import *
> 
> v = [1,0,0]
> angle = 3*pi/2
> q = Quaternion.from_axis_angle(v,angle)
> m = q.to_rotation_matrix()
> print (m.det())
> 
> in a debian 10 with version 1.3-2 of python3-sympy,
> I get -1 as a result. But this is not correct, beacause the determinant
> of a rotation is 1.
> 
> 
> With sympy version 1.5.1-2.1 of ubuntu-20.04, I get the correct result.
> 
> I think this is a bug in debian 10 python3-symp and python-sympy 1.3-2

Tested on Debian unstable with python3-sympy 1.6.2-3, got 1, which is, I
suppose, the correct answer. Thus the fix must have happened between
sympy versions 1.3-2 and 1.6.2-3.

Debian 11 will most likely have python3-sympy 1.6.2-3 or later, thus
this issue will be offset there.

If you still want to have python3-sympy fixed in Debian 10, a patch has
to be prepared dealing specifically with this issue, as upstream version
cannot be bumped in stable release. However, as Debian 11 will be out
soon-ish, I am not sure this is worth the effort.

Hope this helps,
Andrius