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gh-139074: Fix missing high precision case in sumprod() #139075

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Merged
merged 2 commits into from
Sep 17, 2025
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gh-139074: Fix missing high precision case in sumprod() #139075

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c5ecf48
Missing case of an int/int input following a float input.
rhettinger Sep 17, 2025
c842c3f
Add blurb
rhettinger Sep 17, 2025
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4 changes: 3 additions & 1 deletion Lib/test/test_math.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1485,7 +1485,9 @@ def __rmul__(self, other):

# Error cases that arose during development
args = ((-5, -5, 10), (1.5, 4611686018427387904, 2305843009213693952))
self.assertEqual(sumprod(*args), 0.0)
self.assertEqual(sumprod(*args), -7.5)
self.assertEqual(sumprod([-0.01, 1, -1, 0.01], [1, 1, 1, 1]), 0.0)
self.assertEqual(sumprod([1, 1, 1, 1], [-0.01, 1, -1, 0.01], ), 0.0)

@requires_IEEE_754
@unittest.skipIf(HAVE_DOUBLE_ROUNDING,
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2025-09-17-13-21-26.gh-issue-139074.dVZO5F.rst
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@@ -0,0 +1,2 @@
Fixed a missing case in :func:`math.sumprod` where a low precision path was
taken when an int/int input pair followed a float input.
29 changes: 14 additions & 15 deletions Modules/mathmodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2937,32 +2937,31 @@ math_sumprod_impl(PyObject *module, PyObject *p, PyObject *q)

if (!finished) {
double flt_p, flt_q;
bool p_type_float = PyFloat_CheckExact(p_i);
bool q_type_float = PyFloat_CheckExact(q_i);
if (p_type_float && q_type_float) {
flt_p = PyFloat_AS_DOUBLE(p_i);
flt_q = PyFloat_AS_DOUBLE(q_i);
} else if (p_type_float && (PyLong_CheckExact(q_i) || PyBool_Check(q_i))) {
/* We care about float/int pairs and int/float pairs because
they arise naturally in several use cases such as price
times quantity, measurements with integer weights, or
data selected by a vector of bools. */

if (PyFloat_CheckExact(p_i)) {
flt_p = PyFloat_AS_DOUBLE(p_i);
flt_q = PyLong_AsDouble(q_i);
if (flt_q == -1.0 && PyErr_Occurred()) {
} else if (PyLong_CheckExact(p_i) || PyBool_Check(p_i)) {
flt_p = PyLong_AsDouble(p_i);
if (flt_p == -1.0 && PyErr_Occurred()) {
PyErr_Clear();
goto finalize_flt_path;
}
} else if (q_type_float && (PyLong_CheckExact(p_i) || PyBool_Check(p_i))) {
} else {
goto finalize_flt_path;
}

if (PyFloat_CheckExact(q_i)) {
flt_q = PyFloat_AS_DOUBLE(q_i);
flt_p = PyLong_AsDouble(p_i);
if (flt_p == -1.0 && PyErr_Occurred()) {
} else if (PyLong_CheckExact(q_i) || PyBool_Check(q_i)) {
flt_q = PyLong_AsDouble(q_i);
if (flt_q == -1.0 && PyErr_Occurred()) {
PyErr_Clear();
goto finalize_flt_path;
}
} else {
goto finalize_flt_path;
}

TripleLength new_flt_total = tl_fma(flt_p, flt_q, flt_total);
if (isfinite(new_flt_total.hi)) {
flt_total = new_flt_total;
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