mirror of https://github.com/python/cpython
gh-119372: Recover inf's and zeros in _Py_c_quot (GH-119457)
In some cases, previously computed as (nan+nanj), we could recover meaningful component values in the result, see e.g. the C11, Annex G.5.2, routine _Cdivd().
This commit is contained in:
parent
0a1e8ff9c1
commit
2cb84b107a
|
@ -94,6 +94,10 @@ class ComplexTest(unittest.TestCase):
|
|||
msg += ': zeros have different signs'
|
||||
self.fail(msg.format(x, y))
|
||||
|
||||
def assertComplexesAreIdentical(self, x, y):
|
||||
self.assertFloatsAreIdentical(x.real, y.real)
|
||||
self.assertFloatsAreIdentical(x.imag, y.imag)
|
||||
|
||||
def assertClose(self, x, y, eps=1e-9):
|
||||
"""Return true iff complexes x and y "are close"."""
|
||||
self.assertCloseAbs(x.real, y.real, eps)
|
||||
|
@ -139,6 +143,33 @@ class ComplexTest(unittest.TestCase):
|
|||
self.assertTrue(isnan(z.real))
|
||||
self.assertTrue(isnan(z.imag))
|
||||
|
||||
self.assertComplexesAreIdentical(complex(INF, 1)/(0.0+1j),
|
||||
complex(NAN, -INF))
|
||||
|
||||
# test recover of infs if numerator has infs and denominator is finite
|
||||
self.assertComplexesAreIdentical(complex(INF, -INF)/(1+0j),
|
||||
complex(INF, -INF))
|
||||
self.assertComplexesAreIdentical(complex(INF, INF)/(0.0+1j),
|
||||
complex(INF, -INF))
|
||||
self.assertComplexesAreIdentical(complex(NAN, INF)/complex(2**1000, 2**-1000),
|
||||
complex(INF, INF))
|
||||
self.assertComplexesAreIdentical(complex(INF, NAN)/complex(2**1000, 2**-1000),
|
||||
complex(INF, -INF))
|
||||
|
||||
# test recover of zeros if denominator is infinite
|
||||
self.assertComplexesAreIdentical((1+1j)/complex(INF, INF), (0.0+0j))
|
||||
self.assertComplexesAreIdentical((1+1j)/complex(INF, -INF), (0.0+0j))
|
||||
self.assertComplexesAreIdentical((1+1j)/complex(-INF, INF),
|
||||
complex(0.0, -0.0))
|
||||
self.assertComplexesAreIdentical((1+1j)/complex(-INF, -INF),
|
||||
complex(-0.0, 0))
|
||||
self.assertComplexesAreIdentical((INF+1j)/complex(INF, INF),
|
||||
complex(NAN, NAN))
|
||||
self.assertComplexesAreIdentical(complex(1, INF)/complex(INF, INF),
|
||||
complex(NAN, NAN))
|
||||
self.assertComplexesAreIdentical(complex(INF, 1)/complex(1, INF),
|
||||
complex(NAN, NAN))
|
||||
|
||||
def test_truediv_zero_division(self):
|
||||
for a, b in ZERO_DIVISION:
|
||||
with self.assertRaises(ZeroDivisionError):
|
||||
|
|
|
@ -0,0 +1,2 @@
|
|||
Correct invalid corner cases in complex division (resulted in ``(nan+nanj)``
|
||||
output), e.g. ``1/complex('(inf+infj)')``. Patch by Sergey B Kirpichev.
|
|
@ -88,8 +88,7 @@ _Py_c_quot(Py_complex a, Py_complex b)
|
|||
* numerators and denominator by whichever of {b.real, b.imag} has
|
||||
* larger magnitude. The earliest reference I found was to CACM
|
||||
* Algorithm 116 (Complex Division, Robert L. Smith, Stanford
|
||||
* University). As usual, though, we're still ignoring all IEEE
|
||||
* endcases.
|
||||
* University).
|
||||
*/
|
||||
Py_complex r; /* the result */
|
||||
const double abs_breal = b.real < 0 ? -b.real : b.real;
|
||||
|
@ -120,6 +119,28 @@ _Py_c_quot(Py_complex a, Py_complex b)
|
|||
/* At least one of b.real or b.imag is a NaN */
|
||||
r.real = r.imag = Py_NAN;
|
||||
}
|
||||
|
||||
/* Recover infinities and zeros that computed as nan+nanj. See e.g.
|
||||
the C11, Annex G.5.2, routine _Cdivd(). */
|
||||
if (isnan(r.real) && isnan(r.imag)) {
|
||||
if ((isinf(a.real) || isinf(a.imag))
|
||||
&& isfinite(b.real) && isfinite(b.imag))
|
||||
{
|
||||
const double x = copysign(isinf(a.real) ? 1.0 : 0.0, a.real);
|
||||
const double y = copysign(isinf(a.imag) ? 1.0 : 0.0, a.imag);
|
||||
r.real = Py_INFINITY * (x*b.real + y*b.imag);
|
||||
r.imag = Py_INFINITY * (y*b.real - x*b.imag);
|
||||
}
|
||||
else if ((isinf(abs_breal) || isinf(abs_bimag))
|
||||
&& isfinite(a.real) && isfinite(a.imag))
|
||||
{
|
||||
const double x = copysign(isinf(b.real) ? 1.0 : 0.0, b.real);
|
||||
const double y = copysign(isinf(b.imag) ? 1.0 : 0.0, b.imag);
|
||||
r.real = 0.0 * (a.real*x + a.imag*y);
|
||||
r.imag = 0.0 * (a.imag*x - a.real*y);
|
||||
}
|
||||
}
|
||||
|
||||
return r;
|
||||
}
|
||||
#ifdef _M_ARM64
|
||||
|
|
Loading…
Reference in New Issue