Serhiy Storchaka added the comment:
Sorry, I was wrong. I missed that z is in range -1..1. Original report is
invalid, random.vonmisesvariate() always returns a value on the full circle.
However there is some inconsistency. For small kappa (<= 1e-6) result range is
0 to 2pi, for other kappa it is (mu%2pi)-pi to (mu%2pi)+pi. For consistency we
should either shift a range for small kappa:
if kappa <= 1e-6:
return (mu % TWOPI) - _pi + TWOPI * random()
or normalize a result in another case:
if u3 > 0.5:
theta = (mu + _acos(f)) % TWOPI
else:
theta = (mu - _acos(f)) % TWOPI
----------
title: random.vonmisesvariate() returns a value only on the half-circle ->
random.vonmisesvariate() results range is inconsistent for small and not small
kappa
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Python tracker <[email protected]>
<http://bugs.python.org/issue17149>
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