Generic floating point handling in Python
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Author: Andrew Fitzgibbon
Requires Python: >=3.8.1
Classifiers
Intended Audience
- Developers
License
- OSI Approved :: MIT License
Programming Language
- Python :: 3
Development Status
- 3 - Alpha
gfloat: Generic floating-point types in Python
An implementation of generic floating point encode/decode logic, handling various current and proposed floating point types:
- IEEE 754: Binary16, Binary32
- OCP Float8: E5M2, E4M3
- IEEE WG P3109: P3109_{K}p{P} for K > 2, and 1 <= P < K.
- OCP MX Formats: E2M1, M2M3, E3M2, E8M0, INT8, and the MX block formats.
The library favours readability and extensibility over speed (although the *_ndarray functions are reasonably fast for large arrays, see the benchmarking notebook). For other implementations of these datatypes more focused on speed see, for example, ml_dtypes, bitstring, MX PyTorch Emulation Library.
See https://gfloat.readthedocs.io for documentation, or dive into the notebooks to explore the formats.
For example, here's a table from the 02-value-stats notebook:
| name | B: Bits in the format | P: Precision in bits | E: Exponent field width in bits | Exact in float16? | Exact in float32? | 0<x<1 | 1<x<Inf | minSubnormal | maxSubnormal | minNormal | maxNormal | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| name | B | P | E | rt16 | rt32 | lt1 | gt1 | minSubnormal | maxSubnormal | minNormal | maxNormal | |
| -------------- | ----- | ----- | ----- | -------- | -------- | ------- | ------- | ---------------- | ---------------- | ------------- | --------------- | |
| p3109_k3p2sf | 3 | 2 | 1 | True | True | 1 | 1 | 0.5 | 0.5 | 1 | 1.5 | |
| ocp_e2m1 | 4 | 2 | 2 | True | True | 1 | 5 | 0.5 | 0.5 | 1 | 6 | |
| p3109_k4p2sf | 4 | 2 | 2 | True | True | 3 | 3 | 0.25 | 0.25 | 0.5 | 3 | |
| ocp_e2m3 | 6 | 4 | 2 | True | True | 7 | 23 | 0.125 | 0.875 | 1 | 7.5 | |
| ocp_e3m2 | 6 | 3 | 3 | True | True | 11 | 19 | 0.0625 | 0.1875 | 0.25 | 28 | |
| p3109_k6p3sf | 6 | 3 | 3 | True | True | 15 | 15 | 0.03125 | 0.09375 | 0.125 | 14 | |
| p3109_k6p4sf | 6 | 4 | 2 | True | True | 15 | 15 | 0.0625 | 0.4375 | 0.5 | 3.75 | |
| ocp_e4m3 | 8 | 4 | 4 | True | True | 55 | 70 | 2^-9 | 7/4*2^-7 | 0.015625 | 448 | |
| ocp_e5m2 | 8 | 3 | 5 | True | True | 59 | 63 | 2^-16 | 3/2*2^-15 | 2^-14 | 57344 | |
| p3109_k8p1se | 8 | 1 | 7 | False | True | 63 | 62 | n/a | n/a | 2^-63 | 2^62 | |
| p3109_k8p1ue | 8 | 1 | 8 | False | True | 127 | 125 | n/a | n/a | 2^-127 | 2^125 | |
| p3109_k8p3se | 8 | 3 | 5 | True | True | 63 | 62 | 2^-17 | 3/2*2^-16 | 2^-15 | 49152 | |
| p3109_k8p3sf | 8 | 3 | 5 | True | True | 63 | 63 | 2^-17 | 3/2*2^-16 | 2^-15 | 57344 | |
| p3109_k8p3ue | 8 | 3 | 6 | False | True | 127 | 125 | 2^-33 | 3/2*2^-32 | 2^-31 | 5/4*2^31 | |
| p3109_k8p3uf | 8 | 3 | 6 | False | True | 127 | 126 | 2^-33 | 3/2*2^-32 | 2^-31 | 3/2*2^31 | |
| p3109_k8p4se | 8 | 4 | 4 | True | True | 63 | 62 | 2^-10 | 7/4*2^-8 | 0.0078125 | 224 | |
| p3109_k8p4sf | 8 | 4 | 4 | True | True | 63 | 63 | 2^-10 | 7/4*2^-8 | 0.0078125 | 240 | |
| p3109_k8p4ue | 8 | 4 | 5 | True | True | 127 | 125 | 2^-18 | 7/4*2^-16 | 2^-15 | 53248 | |
| p3109_k8p4uf | 8 | 4 | 5 | True | True | 127 | 126 | 2^-18 | 7/4*2^-16 | 2^-15 | 57344 | |
| p3109_k8p7sf | 8 | 7 | 1 | True | True | 63 | 63 | 0.015625 | 63/32*2^-1 | 1 | 127/64*2^0 | |
| p3109_k8p8uf | 8 | 8 | 1 | True | True | 127 | 126 | 0.0078125 | 127/64*2^-1 | 1 | 127/64*2^0 | |
| binary16 | 16 | 11 | 5 | True | True | 15359 | 16383 | 2^-24 | 1023/512*2^-15 | 2^-14 | 65504 | |
| bfloat16 | 16 | 8 | 8 | False | True | 16255 | 16383 | 2^-133 | 127/64*2^-127 | 2^-126 | 255/128*2^127 | |
| ocp_e8m0 | 8 | 1 | 8 | False | True | 127 | 127 | n/a | n/a | 2^-127 | 2^127 | |
| ocp_int8 | 8 | 8 | 0 | True | True | 63 | 63 | 0.015625 | 127/64*2^0 | n/a | n/a |
Notes
All NaNs are the same, with no distinction between signalling or quiet, or between differently encoded NaNs.
0.5.2
Aug 21, 2025
0.5.1
Aug 21, 2025
0.5
Aug 21, 2025
0.4
Nov 02, 2024
0.3
Jun 10, 2024
0.2.1
May 21, 2024
0.2
May 21, 2024
0.1
May 02, 2024
0.0.5
Apr 02, 2024
0.0.4
Mar 22, 2024
0.0.3
Feb 08, 2024
0.0.2
Jan 30, 2024
0.0.1
Jan 30, 2024