Float(0).is_integer is True, Float(1.1).is_integer is False, Float(1) is None #25875

smichr · 2023-11-05T03:44:33Z

References to other Issues or PRs

yet another attempt to fix #23731
alternate to #25865, #25864, #25856

Brief description of what is fixed or changed

>>> Float(0).is_integer  # same as master
True
>>> print(Float(1).is_integer)  # False in master
None
>>> Float(1.5).is_integer  # same as master
False

Other comments

There was a long discussion of whether Float should be classified as rational here. One major concern was that float/Float objects do not behave as Rationals in operations, e.g.

>>> S(1e-16) + S(2) == 2.0
True
>>> (x+y).n(subs={x:1e-16,y:2}) == 2.
True

Release Notes

core
- Float.is_integer is now None except for 0.0 and Floats with a non-zero fraction. Previously, only Float(0) was True
- Fixed Eq incorrectly evaluating to False in some cases with floats.

sympy-bot · 2023-11-05T03:44:40Z

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core
- Float.is_integer is now None except for 0.0 and Floats with a non-zero fraction. Previously, only Float(0) was True (#25875 by @smichr)
- Fixed Eq incorrectly evaluating to False in some cases with floats. (#25875 by @smichr)

This will be added to https://github.com/sympy/sympy/wiki/Release-Notes-for-1.13.

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#### References to other Issues or PRs
<!-- If this pull request fixes an issue, write "Fixes #NNNN" in that exact
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yet another attempt to fix #23731
alternate to #25865, #25864, #25856

#### Brief description of what is fixed or changed

```python
>>> Float(0).is_integer  # same as master
True
>>> print(Float(1).is_integer)  # False in master
None
>>> Float(1.5).is_integer  # same as master
False
```

#### Other comments

There was a long discussion of whether `Float` should be classified as `rational` [here](https://groups.google.com/g/sympy/c/RUYOxxwMgac/m/4-1JXtny32EJ). One major concern was that float/Float objects do not behave as Rationals in operations, e.g.
```python
>>> S(1e-16) + S(2) == 2.0
True
>>> (x+y).n(subs={x:1e-16,y:2}) == 2.
True
```

#### Release Notes

<!-- Write the release notes for this release below between the BEGIN and END
statements. The basic format is a bulleted list with the name of the subpackage
and the release note for this PR. For example:

* solvers
  * Added a new solver for logarithmic equations.

* functions
  * Fixed a bug with log of integers. Formerly, `log(-x)` incorrectly gave `-log(x)`.

* physics.units
  * Corrected a semantical error in the conversion between volt and statvolt which
    reported the volt as being larger than the statvolt.

or if no release note(s) should be included use:

NO ENTRY

See https://github.com/sympy/sympy/wiki/Writing-Release-Notes for more
information on how to write release notes. The bot will check your release
notes automatically to see if they are formatted correctly. -->

<!-- BEGIN RELEASE NOTES -->
- core
  - `Float.is_integer` is now `None` except for `0.0` and `Floats` with a non-zero fraction. Previously, only `Float(0)` was True
  - Fixed Eq incorrectly evaluating to `False` in some cases with floats.
<!-- END RELEASE NOTES -->

Update

The release notes on the wiki have been updated.

github-actions · 2023-11-05T05:42:09Z

Benchmark results from GitHub Actions

Lower numbers are good, higher numbers are bad. A ratio less than 1
means a speed up and greater than 1 means a slowdown. Green lines
beginning with + are slowdowns (the PR is slower then master or
master is slower than the previous release). Red lines beginning
with - are speedups.

Significantly changed benchmark results (PR vs master)

Significantly changed benchmark results (master vs previous release)

| Change   | Before [a00718ba]    | After [6f3767c2]    |   Ratio | Benchmark (Parameter)                                                |
|----------|----------------------|---------------------|---------|----------------------------------------------------------------------|
| -        | 69.2±1ms             | 45.6±0.5ms          |    0.66 | integrate.TimeIntegrationRisch02.time_doit(10)                       |
| +        | 17.7±0.2μs           | 30.5±0.2μs          |    1.73 | integrate.TimeIntegrationRisch03.time_doit(1)                        |
| -        | 5.44±0.02ms          | 2.89±0.02ms         |    0.53 | logic.LogicSuite.time_load_file                                      |
| -        | 71.6±0.4ms           | 28.3±0.2ms          |    0.4  | polys.TimeGCD_GaussInt.time_op(1, 'dense')                           |
| -        | 26.2±0.4ms           | 17.1±0.2ms          |    0.65 | polys.TimeGCD_GaussInt.time_op(1, 'expr')                            |
| -        | 72.9±0.3ms           | 28.6±0.2ms          |    0.39 | polys.TimeGCD_GaussInt.time_op(1, 'sparse')                          |
| -        | 253±1ms              | 125±0.4ms           |    0.49 | polys.TimeGCD_GaussInt.time_op(2, 'dense')                           |
| -        | 254±2ms              | 124±1ms             |    0.49 | polys.TimeGCD_GaussInt.time_op(2, 'sparse')                          |
| -        | 652±9ms              | 371±3ms             |    0.57 | polys.TimeGCD_GaussInt.time_op(3, 'dense')                           |
| -        | 658±5ms              | 373±3ms             |    0.57 | polys.TimeGCD_GaussInt.time_op(3, 'sparse')                          |
| -        | 490±6μs              | 283±2μs             |    0.58 | polys.TimeGCD_LinearDenseQuadraticGCD.time_op(1, 'dense')            |
| -        | 1.78±0.03ms          | 1.05±0ms            |    0.59 | polys.TimeGCD_LinearDenseQuadraticGCD.time_op(2, 'dense')            |
| -        | 5.82±0.03ms          | 3.07±0.05ms         |    0.53 | polys.TimeGCD_LinearDenseQuadraticGCD.time_op(3, 'dense')            |
| -        | 445±7μs              | 230±3μs             |    0.52 | polys.TimeGCD_QuadraticNonMonicGCD.time_op(1, 'dense')               |
| -        | 1.46±0.01ms          | 670±2μs             |    0.46 | polys.TimeGCD_QuadraticNonMonicGCD.time_op(2, 'dense')               |
| -        | 4.85±0.01ms          | 1.63±0.01ms         |    0.34 | polys.TimeGCD_QuadraticNonMonicGCD.time_op(3, 'dense')               |
| -        | 371±0.9μs            | 201±0.5μs           |    0.54 | polys.TimeGCD_SparseGCDHighDegree.time_op(1, 'dense')                |
| -        | 2.46±0.02ms          | 1.19±0.01ms         |    0.48 | polys.TimeGCD_SparseGCDHighDegree.time_op(3, 'dense')                |
| -        | 9.78±0.04ms          | 4.34±0.02ms         |    0.44 | polys.TimeGCD_SparseGCDHighDegree.time_op(5, 'dense')                |
| -        | 355±3μs              | 165±1μs             |    0.47 | polys.TimeGCD_SparseNonMonicQuadratic.time_op(1, 'dense')            |
| -        | 2.42±0.01ms          | 876±10μs            |    0.36 | polys.TimeGCD_SparseNonMonicQuadratic.time_op(3, 'dense')            |
| -        | 9.63±0.04ms          | 2.59±0.01ms         |    0.27 | polys.TimeGCD_SparseNonMonicQuadratic.time_op(5, 'dense')            |
| -        | 1.03±0.02ms          | 419±3μs             |    0.41 | polys.TimePREM_LinearDenseQuadraticGCD.time_op(3, 'dense')           |
| -        | 1.71±0.01ms          | 508±1μs             |    0.3  | polys.TimePREM_LinearDenseQuadraticGCD.time_op(3, 'sparse')          |
| -        | 5.77±0.05ms          | 1.77±0.01ms         |    0.31 | polys.TimePREM_LinearDenseQuadraticGCD.time_op(5, 'dense')           |
| -        | 8.38±0.08ms          | 1.53±0.01ms         |    0.18 | polys.TimePREM_LinearDenseQuadraticGCD.time_op(5, 'sparse')          |
| -        | 289±2μs              | 63.2±0.2μs          |    0.22 | polys.TimePREM_QuadraticNonMonicGCD.time_op(1, 'sparse')             |
| -        | 3.40±0.04ms          | 388±3μs             |    0.11 | polys.TimePREM_QuadraticNonMonicGCD.time_op(3, 'dense')              |
| -        | 3.88±0.02ms          | 281±2μs             |    0.07 | polys.TimePREM_QuadraticNonMonicGCD.time_op(3, 'sparse')             |
| -        | 6.73±0.05ms          | 1.25±0.01ms         |    0.19 | polys.TimePREM_QuadraticNonMonicGCD.time_op(5, 'dense')              |
| -        | 8.60±0.1ms           | 835±1μs             |    0.1  | polys.TimePREM_QuadraticNonMonicGCD.time_op(5, 'sparse')             |
| -        | 5.13±0.06ms          | 2.99±0.01ms         |    0.58 | polys.TimeSUBRESULTANTS_LinearDenseQuadraticGCD.time_op(2, 'sparse') |
| -        | 11.9±0.08ms          | 6.43±0.03ms         |    0.54 | polys.TimeSUBRESULTANTS_LinearDenseQuadraticGCD.time_op(3, 'dense')  |
| -        | 22.4±0.08ms          | 9.18±0.06ms         |    0.41 | polys.TimeSUBRESULTANTS_LinearDenseQuadraticGCD.time_op(3, 'sparse') |
| -        | 5.33±0.02ms          | 872±4μs             |    0.16 | polys.TimeSUBRESULTANTS_QuadraticNonMonicGCD.time_op(1, 'sparse')    |
| -        | 12.8±0.07ms          | 7.04±0.03ms         |    0.55 | polys.TimeSUBRESULTANTS_QuadraticNonMonicGCD.time_op(2, 'sparse')    |
| -        | 100±1ms              | 25.4±0.05ms         |    0.25 | polys.TimeSUBRESULTANTS_QuadraticNonMonicGCD.time_op(3, 'dense')     |
| -        | 166±0.6ms            | 54.9±0.2ms          |    0.33 | polys.TimeSUBRESULTANTS_QuadraticNonMonicGCD.time_op(3, 'sparse')    |
| -        | 170±0.7μs            | 111±0.4μs           |    0.65 | polys.TimeSUBRESULTANTS_SparseGCDHighDegree.time_op(1, 'dense')      |
| -        | 360±2μs              | 214±0.7μs           |    0.59 | polys.TimeSUBRESULTANTS_SparseGCDHighDegree.time_op(1, 'sparse')     |
| -        | 4.18±0.01ms          | 830±4μs             |    0.2  | polys.TimeSUBRESULTANTS_SparseGCDHighDegree.time_op(3, 'dense')      |
| -        | 5.31±0.1ms           | 384±1μs             |    0.07 | polys.TimeSUBRESULTANTS_SparseGCDHighDegree.time_op(3, 'sparse')     |
| -        | 19.6±0.06ms          | 2.81±0.01ms         |    0.14 | polys.TimeSUBRESULTANTS_SparseGCDHighDegree.time_op(5, 'dense')      |
| -        | 22.3±0.1ms           | 629±3μs             |    0.03 | polys.TimeSUBRESULTANTS_SparseGCDHighDegree.time_op(5, 'sparse')     |
| -        | 489±4μs              | 134±0.7μs           |    0.27 | polys.TimeSUBRESULTANTS_SparseNonMonicQuadratic.time_op(1, 'sparse') |
| -        | 4.56±0.04ms          | 609±2μs             |    0.13 | polys.TimeSUBRESULTANTS_SparseNonMonicQuadratic.time_op(3, 'dense')  |
| -        | 5.29±0.02ms          | 137±0.9μs           |    0.03 | polys.TimeSUBRESULTANTS_SparseNonMonicQuadratic.time_op(3, 'sparse') |
| -        | 12.7±0.07ms          | 1.30±0.01ms         |    0.1  | polys.TimeSUBRESULTANTS_SparseNonMonicQuadratic.time_op(5, 'dense')  |
| -        | 13.8±0.04ms          | 139±1μs             |    0.01 | polys.TimeSUBRESULTANTS_SparseNonMonicQuadratic.time_op(5, 'sparse') |
| -        | 133±0.4μs            | 75.2±1μs            |    0.56 | solve.TimeMatrixOperations.time_rref(3, 0)                           |
| -        | 250±0.9μs            | 87.9±0.4μs          |    0.35 | solve.TimeMatrixOperations.time_rref(4, 0)                           |
| -        | 24.1±0.06ms          | 10.1±0.04ms         |    0.42 | solve.TimeSolveLinSys189x49.time_solve_lin_sys                       |

Full benchmark results can be found as artifacts in GitHub Actions
(click on checks at the top of the PR).

asmeurer · 2023-11-06T06:18:30Z

The point should also be made that Float(1).is_integer = None does not preclude making it True in the future, since None means "True or False". So I think this is the safest fix, and it matches what we decided in the past for Float.is_rational = False.

I don't know if making Float.is_integer = False was done intentionally or accidentally, but it's clearly wrong given the Eq behavior, and that sort of thing could happen anywhere in the code that uses an is_integer check.

sympy/assumptions/handlers/ntheory.py

sympy/assumptions/tests/test_query.py

asmeurer · 2023-11-06T21:38:49Z

Thanks for picking up this work @smichr

For future readers, if we ever in the future decide that making Float(1).is_integer = True (or even Float.is_rational = True in general) we can revisit that. I think it could be dangerous, since floats don't actually satisfy the same mathematical properties as integers and rationals, although I'm not completely sure yet just how much that would matter in practice.

smichr added 2 commits November 4, 2023 18:22

Float.is_integer None except for 0 and nonint

05b64e9

make check_dim Float aware

6ccd922

smichr force-pushed the 23731 branch from 97a56f4 to eb83082 Compare November 5, 2023 04:12

smichr added 3 commits November 4, 2023 23:34

test failure related changes

9a9a7e2

add testing for type to is_eq

06d2f8d

cleanup syntax

ae5e7a0

smichr force-pushed the 23731 branch from eb83082 to ae5e7a0 Compare November 5, 2023 04:34

smichr marked this pull request as ready for review November 5, 2023 13:25

This was referenced Nov 5, 2023

recognize Float as rational #25865

Closed

avoid evaluating Eq with Float args #25864

Closed

Make Float.is_integer always return None #25856

Closed

fix EvenPredicate to return None for Float(1)

a4f255b

smichr commented Nov 6, 2023

View reviewed changes

sympy/assumptions/handlers/ntheory.py Outdated Show resolved Hide resolved

Update sympy/assumptions/handlers/ntheory.py

4f91444

smichr enabled auto-merge November 6, 2023 15:34

smichr commented Nov 6, 2023

View reviewed changes

sympy/assumptions/tests/test_query.py Outdated Show resolved Hide resolved

Update sympy/assumptions/tests/test_query.py

b8d349d

smichr merged commit 72c0253 into sympy:master Nov 6, 2023

smichr deleted the 23731 branch November 6, 2023 16:36

tbennun mentioned this pull request Nov 6, 2023

is_zero broken for integer/float comparison #23731

Closed

This was referenced Nov 16, 2023

Incorrect evaluation of integer and real equality. #25146

Closed

Workaround sympy modulus bugginess pytorch/pytorch#113878

Closed

ezyang mentioned this pull request Nov 17, 2023

Sympy reasoning with true division is broken pytorch/pytorch#113905

Open

cbm755 mentioned this pull request Jan 29, 2024

Eq versus == behavior following Float "integer" is_integer changes #26146

Open

asmeurer mentioned this pull request May 22, 2024

sympy.Float(0.0).is_integer is True, but sympy.Float(1.0).is_integer is None #26620

Open

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Float(0).is_integer is True, Float(1.1).is_integer is False, Float(1) is None #25875

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Float(0).is_integer is True, Float(1.1).is_integer is False, Float(1) is None #25875

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