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Misc improvements to the float tutorial #102052

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Merged
rhettinger merged 10 commits into from
Feb 19, 2023
Merged

Misc improvements to the float tutorial #102052

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1e2ec34
Example is more intelligible without the leading zeros
rhettinger Feb 19, 2023
082d7a8
Leading zeros are easier to read and match the surrounding text.
rhettinger Feb 19, 2023
2ff520d
Compare sum() to straight addition and to math.fsum()
rhettinger Feb 19, 2023
22e1a96
Show math.isclose() for comparing inexact values
rhettinger Feb 19, 2023
cb1f78a
Add doctests throughout
rhettinger Feb 19, 2023
e9e959a
Add a more useful example of round() for comparisons
rhettinger Feb 19, 2023
8f02dc5
Shorter example
rhettinger Feb 19, 2023
d8bcc4c
Fix doctests: Missing import and counterfactual example.
rhettinger Feb 19, 2023
cd8abc5
Compare sum() and fsum() with straight addition
rhettinger Feb 19, 2023
d6a6b6b
Add section author
rhettinger Feb 19, 2023
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Add a more useful example of round() for comparisons
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@rhettinger
rhettinger committed Feb 19, 2023
commit e9e959a08a86e5a7ad41a813bf0da76c32980141
8 changes: 8 additions & 0 deletions Doc/tutorial/floatingpoint.rst
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Expand Up @@ -136,6 +136,14 @@ the :func:`math.isclose` function can be useful for comparing inexact values:
>>> math.isclose(0.1 + 0.1 + 0.1, 0.3)
True

Alternatively, the :func:`round` function can be used to compare rough
approximations::

.. doctest::

>>> round(math.pi, ndigits=2) == round(22 / 7, ndigits=2)
True

Binary floating-point arithmetic holds many surprises like this. The problem
with "0.1" is explained in precise detail below, in the "Representation Error"
section. See `Examples of Floating Point Problems
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