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bpo-44698: Restore complex pow behaviour for small integral exponents (GH-27772) (GH-27796)

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(cherry picked from commit 4b9a2dcf19)

Co-authored-by: Mark Dickinson <mdickinson@enthought.com>
This commit is contained in:
Miss Islington (bot) 2021-08-17 10:38:03 -07:00 • committed by GitHub
parent f6bd1ca166
commit 3f81e9628f
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3 changed files with 37 additions and 21 deletions
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28
Objects/complexobject.c
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@ -172,14 +172,7 @@ c_powu(Py_complex x, long n)
static Py_complex
c_powi(Py_complex x, long n)
{
Py_complex cn;
if (n > 100 || n < -100) {
cn.real = (double) n;
cn.imag = 0.;
return _Py_c_pow(x,cn);
}
else if (n > 0)
if (n > 0)
return c_powu(x,n);
else
return _Py_c_quot(c_1, c_powu(x,-n));
@ -523,19 +516,12 @@ complex_pow(PyObject *v, PyObject *w, PyObject *z)
return NULL;
}
errno = 0;
// Check if w is an integer value that fits inside a C long, so we can
// use a faster algorithm. TO_COMPLEX(w, b), above, already handled the
// conversion from larger longs, as well as other types.
if (PyLong_Check(w)) {
int overflow = 0;
long int_exponent = PyLong_AsLongAndOverflow(w, &overflow);
if (int_exponent == -1 && PyErr_Occurred())
return NULL;
if (overflow == 0)
p = c_powi(a, int_exponent);
else
p = _Py_c_pow(a, b);
} else {
// Check whether the exponent has a small integer value, and if so use
// a faster and more accurate algorithm.
if (b.imag == 0.0 && b.real == floor(b.real) && fabs(b.real) <= 100.0) {
p = c_powi(a, (long)b.real);
}
else {
p = _Py_c_pow(a, b);
}