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Merged revisions 87032 via svnmerge from

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  r87032 | mark.dickinson | 2010-12-04 12:25:30 +0000 (Sat, 04 Dec 2010) | 3 lines

  Issue #10596: Fix float.__mod__ to have the same behaviour as
  float.__divmod__ with respect to signed zeros.
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This commit is contained in:
Mark Dickinson 2010-12-04 13:04:18 +00:00
parent 33154388f9
commit 0169af1534
3 changed files with 43 additions and 4 deletions
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18
Objects/floatobject.c
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@ -600,10 +600,20 @@ float_rem(PyObject *v, PyObject *w)
#endif
PyFPE_START_PROTECT("modulo", return 0)
mod = fmod(vx, wx);
/* note: checking mod*wx < 0 is incorrect -- underflows to
0 if wx < sqrt(smallest nonzero double) */
if (mod && ((wx < 0) != (mod < 0))) {
mod += wx;
if (mod) {
/* ensure the remainder has the same sign as the denominator */
if ((wx < 0) != (mod < 0)) {
mod += wx;
}
}
else {
/* the remainder is zero, and in the presence of signed zeroes
fmod returns different results across platforms; ensure
it has the same sign as the denominator; we'd like to do
"mod = wx * 0.0", but that may get optimized away */
mod *= mod; /* hide "mod = +0" from optimizer */
if (wx < 0.0)
mod = -mod;
}
PyFPE_END_PROTECT(mod)
return PyFloat_FromDouble(mod);