Message131954
(-1)**.5 is the same than complex(-1,0)**.5, but it is computed differently than cmath.sqrt(-1).
-1.**0.5 computes:
vabs = math.hypot(-1, 0)
len = pow(vabs, 0.5)
at = math.atan2(0, -1)
phase = at * 0.5
return complex(len*math.cos(phase), len*math.sin(phase))
whereas cmath.sqrt(-1) computes:
ax = math.fabs(-1)
ay = math.fabs(0)
ax /= 8.
s = 2. * math.sqrt(ax + math.hypot(ax, ay/8.))
d = ay / (2.*s)
return complex(d, math.copysign(s, 0))
Anyway, math.sqrt() and cmath.sqrt() are designed to be more precise than x**0.5. |
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Date |
User |
Action |
Args |
2011-03-24 02:51:21 | vstinner | set | recipients:
+ vstinner, mark.dickinson, JBernardo |
2011-03-24 02:51:21 | vstinner | set | messageid: <1300935081.12.0.299799534417.issue11658@psf.upfronthosting.co.za> |
2011-03-24 02:51:20 | vstinner | link | issue11658 messages |
2011-03-24 02:51:20 | vstinner | create | |
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