4 Commits

Author	SHA1	Message	Date
Yoctopuce dev	dbbaa959c8	py/formatfloat: Improve accuracy of float formatting code. ... Following discussions in PR #16666, this commit updates the float formatting code to improve the `repr` reversibility, i.e. the percentage of valid floating point numbers that do parse back to the same number when formatted by `repr` (in CPython it's 100%). This new code offers a choice of 3 float conversion methods, depending on the desired tradeoff between code size and conversion precision: - BASIC method is the smallest code footprint - APPROX method uses an iterative method to approximate the exact representation, which is a bit slower but but does not have a big impact on code size. It provides `repr` reversibility on >99.8% of the cases in double precision, and on >98.5% in single precision (except with REPR_C, where reversibility is 100% as the last two bits are not taken into account). - EXACT method uses higher-precision floats during conversion, which provides perfect results but has a higher impact on code size. It is faster than APPROX method, and faster than the CPython equivalent implementation. It is however not available on all compilers when using FLOAT_IMPL_DOUBLE. Here is the table comparing the impact of the three conversion methods on code footprint on PYBV10 (using single-precision floats) and reversibility rate for both single-precision and double-precision floats. The table includes current situation as a baseline for the comparison: PYBV10 REPR_C FLOAT DOUBLE current = 364688 12.9% 27.6% 37.9% basic = 364812 85.6% 60.5% 85.7% approx = 365080 100.0% 98.5% 99.8% exact = 366408 100.0% 100.0% 100.0% Signed-off-by: Yoctopuce dev <dev@yoctopuce.com>	2025-08-01 00:47:33 +10:00
David Lechner	3dc324d3f1	tests: Format all Python code with black, except tests in basics subdir. ... This adds the Python files in the tests/ directory to be formatted with ./tools/codeformat.py. The basics/ subdirectory is excluded for now so we aren't changing too much at once. In a few places `# fmt: off`/`# fmt: on` was used where the code had special formatting for readability or where the test was actually testing the specific formatting.	2020-03-30 13:21:58 +11:00
Damien George	6ed4581f54	py/formatfloat: Fix number of digits and exponent sign when rounding. ... This patch fixes 2 things when printing a floating-point number that requires rounding up of the mantissa: - retain the correct precision; eg 0.99 becomes 1.0, not 1.00 - if the exponent goes from -1 to 0 then render it as +0, not -0	2017-06-13 13:36:56 +10:00
Rami Ali	64dc925c4a	tests/float: Improve formatfloat.c test coverage using Python.	2017-01-05 12:31:05 +11:00