wrong result from real part
Reported in Sage issue #12807:
sage: a = exp(i*2*pi/3) sage: b = exp(i*pi/3) sage: c = 2*a-b sage: c.real() 1/2
sage: N(c).real() -1.50000000000000
Note that we can compute the real part of
b correctly. Something goes wrong when combining the result. Probably because Python
int's get involved at some point.
sage: a.real() -1/2 sage: b.real() 1/2