Mercurial > hg > octave-lyh > gnulib-hg
changeset 9332:b72a5920bf45
Fix incorrect rounding of floor, floorf, floorl in some cases. Add new test.
| author | Bruno Haible <bruno@clisp.org> |
|---|---|
| date | Sat, 13 Oct 2007 02:51:46 +0200 |
| parents | 1456df727e8e |
| children | edb32d574f8d |
| files | ChangeLog lib/floor.c modules/floorf-tests |
| diffstat | 3 files changed, 33 insertions(+), 11 deletions(-) [+] |
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--- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,10 @@ 2007-10-12 Bruno Haible <bruno@clisp.org> + * lib/floor.c (FUNC): Avoid rounding errors for values near a power + of 2. + * tests/test-floorf2.c: New file. + * modules/floorf-tests: (Files, Depends-on, Makefile.am): Add new test. + * tests/test-floorf1.c: Renamed from tests/test-floorf.c. * modules/floorf-tests: Update.
--- a/lib/floor.c +++ b/lib/floor.c @@ -63,20 +63,31 @@ volatile DOUBLE y = x; volatile DOUBLE z = y; - /* Round to the next integer (nearest or up or down, doesn't matter). */ if (z > L_(0.0)) { - z += TWO_MANT_DIG; - z -= TWO_MANT_DIG; + /* Avoid rounding errors for values near 2^k, where k >= MANT_DIG-1. */ + if (z < TWO_MANT_DIG) + { + /* Round to the next integer (nearest or up or down, doesn't matter). */ + z += TWO_MANT_DIG; + z -= TWO_MANT_DIG; + /* Enforce rounding down. */ + if (z > y) + z -= L_(1.0); + } } else if (z < L_(0.0)) { - z -= TWO_MANT_DIG; - z += TWO_MANT_DIG; + /* Avoid rounding errors for values near -2^k, where k >= MANT_DIG-1. */ + if (z > - TWO_MANT_DIG) + { + /* Round to the next integer (nearest or up or down, doesn't matter). */ + z -= TWO_MANT_DIG; + z += TWO_MANT_DIG; + /* Enforce rounding down. */ + if (z > y) + z -= L_(1.0); + } } - /* Enforce rounding down. */ - if (z > y) - z -= L_(1.0); - return z; }
--- a/modules/floorf-tests +++ b/modules/floorf-tests @@ -1,14 +1,20 @@ Files: tests/test-floorf1.c +tests/test-floorf2.c Depends-on: +float +isnanf-nolibm +stdbool +stdint configure.ac: Makefile.am: -TESTS += test-floorf1 -check_PROGRAMS += test-floorf1 +TESTS += test-floorf1 test-floorf2 +check_PROGRAMS += test-floorf1 test-floorf2 test_floorf1_LDADD = $(LDADD) @FLOORF_LIBM@ +test_floorf2_LDADD = $(LDADD) @FLOORF_LIBM@ License: LGPL