Message 407025 - Python tracker

Note that, on Windows, ldexp() in the presence of denorms can truncate. Division rounds, so

    assert x / 2**i == ldexp(x, -i)

can fail.

>>> import math
>>> d = math.nextafter(0.0, 1.0)
>>> d
5e-324
>>> d3 = 7 * d # .0000...0111
>>> d3
3.5e-323
>>> d3 / 4.0   # rounds
1e-323
>>> math.ldexp(d3, -2)  # truncates
5e-324

or, perhaps more dramatically,

>>> d3 / 8.0, math.ldexp(d3, -3)
(5e-324, 0.0)