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| author | warren <warren.weckesser@gmail.com> | 2021-11-06 02:59:05 -0400 |
|---|---|---|
| committer | warren <warren.weckesser@gmail.com> | 2021-11-06 03:20:51 -0400 |
| commit | 4b9e56921e6343b980b27e308534ca433a4a1fe8 (patch) | |
| tree | bfaf0b87c2dad22890b9629df7a07454b3560ba5 /numpy/random/src/distributions | |
| parent | 7c211013d559db238daf76fdb90af1d2f37a341e (diff) | |
| download | numpy-4b9e56921e6343b980b27e308534ca433a4a1fe8.tar.gz | |
BUG: Get full precision for 32 bit floating point random values.
The formula to convert a 32 bit random integer to a random float32,
(next_uint32(bitgen_state) >> 9) * (1.0f / 8388608.0f)
shifts by one bit too many, resulting in uniform float32 samples always
having a 0 in the least significant bit. The formula is corrected to
(next_uint32(bitgen_state) >> 8) * (1.0f / 16777216.0f)
Occurrences of the incorrect formula in numpy/random/tests/test_direct.py
were also corrected.
Closes gh-17478.
Diffstat (limited to 'numpy/random/src/distributions')
| -rw-r--r-- | numpy/random/src/distributions/distributions.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/numpy/random/src/distributions/distributions.c b/numpy/random/src/distributions/distributions.c index adf4db4a7..bd1e1faa4 100644 --- a/numpy/random/src/distributions/distributions.c +++ b/numpy/random/src/distributions/distributions.c @@ -17,7 +17,7 @@ static NPY_INLINE uint64_t next_uint64(bitgen_t *bitgen_state) { } static NPY_INLINE float next_float(bitgen_t *bitgen_state) { - return (next_uint32(bitgen_state) >> 9) * (1.0f / 8388608.0f); + return (next_uint32(bitgen_state) >> 8) * (1.0f / 16777216.0f); } /* Random generators for external use */ |