diff options
| author | Matthew Brett <matthew.brett@gmail.com> | 2017-02-03 20:02:09 +0000 |
|---|---|---|
| committer | Charles Harris <charlesr.harris@gmail.com> | 2017-02-03 13:02:09 -0700 |
| commit | a611932bbcb132f82472a1f222a31e120fb6dc86 (patch) | |
| tree | 39dd116f929a2f03be1c59d360e83827f28763af /doc | |
| parent | eefc4b8bea043a324927e40d998ed760799f0b82 (diff) | |
| download | numpy-a611932bbcb132f82472a1f222a31e120fb6dc86.tar.gz | |
ENH: hard-code finfo parameters for known types (#8504)
* ENH: hard-code finfo parameters for known types
Hard-code the MachAr parameters for float64, float32, 80-bit extended
precision, to save time, and provide skeleton for more difficult types
such as the double double on PPC; see
https://github.com/numpy/numpy/issues/2669
* ENH: add PPC long double finfo
Add parameters for PPC long double, fixing long-standing bug for finfo
on PPC.
* BF: use Python floats for float64 finfo
For some reason (garrgh) np.exp2 with float64 gives a different answer on
Windows than it does on other platforms; use Python floating point
calculations instead, which do appear to be consistent.
* DOC: add release notes for finfo fixes
Add release note describing fixes for PPC long double ``finfo``.
* RF: try using byte string to identify floats
From suggestion by Chuck, and
https//perl5.git.perl.org/perl.git/blob/3118d7d684b56cbeb702af874f4326683c45f045:/Configure
* TST: add tests for reasonable finfo parameters
Check that finfo returns somewhat reasonable parameters for all floating
point types.
* RF: add warning for not-recognized float type
Warn if we don't have a signature for the float type.
* NF: add IEEE float128 type signature
Still needs test on platform with IEEE float128, to check MachAr-like
parameters are correct.
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/release/1.13.0-notes.rst | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/doc/release/1.13.0-notes.rst b/doc/release/1.13.0-notes.rst index 69e2a6b5b..ac4d4b2c1 100644 --- a/doc/release/1.13.0-notes.rst +++ b/doc/release/1.13.0-notes.rst @@ -105,6 +105,22 @@ Performance improvements for ``packbits`` and ``unpackbits`` The functions ``numpy.packbits`` with boolean input and ``numpy.unpackbits`` have been optimized to be a significantly faster for contiguous data. +Fix for PPC long double floating point information +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +In previous versions of numpy, the ``finfo`` function returned invalid +information about the `double double`_ format of the ``longdouble`` float type +on Power PC (PPC). The invalid values resulted from the failure of the numpy +algorithm to deal with the `variable number of digits in the significand +<https://www.ibm.com/support/knowledgecenter/en/ssw_aix_71/com.ibm.aix.genprogc/128bit_long_double_floating-point_datatype.htm>`_ +that are a feature of PPC long doubles. This release by-passes the failing +algorithm by using heuristics to detect the presence of the PPC double double +format. A side-effect of using these heuristics is that the ``finfo`` +function is faster than previous releases. + +.. _issues: https://github.com/numpy/numpy/issues/2669 + +.. _double double: https://en.wikipedia.org/wiki/Quadruple-precision_floating-point_format#Double-double_arithmetic + Changes ======= |