From a18af12277fccdef4cb03dccba2458079d231889 Mon Sep 17 00:00:00 2001
From: Sergey B Kirpichev <skirpichev@gmail.com>
Date: Mon, 5 Oct 2026 07:09:30 +0300
Subject: [PATCH] Remove m_remainder()

---
 Modules/mathmodule.c | 97 +-------------------------------------------
 1 file changed, 1 insertion(+), 96 deletions(-)

diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c
index 5e100da7a424172..29914276ff39443 100644
--- a/Modules/mathmodule.c
+++ b/Modules/mathmodule.c
@@ -670,101 +670,6 @@ m_lgamma(double x)
     return r;
 }
 
-/* IEEE 754-style remainder operation: x - n*y where n*y is the nearest
-   multiple of y to x, taking n even in the case of a tie. Assuming an IEEE 754
-   binary floating-point format, the result is always exact. */
-
-static double
-m_remainder(double x, double y)
-{
-    /* Deal with most common case first. */
-    if (isfinite(x) && isfinite(y)) {
-        double absx, absy, c, m, r;
-
-        if (y == 0.0) {
-            return Py_NAN;
-        }
-
-        absx = fabs(x);
-        absy = fabs(y);
-        m = fmod(absx, absy);
-
-        /*
-           Warning: some subtlety here. What we *want* to know at this point is
-           whether the remainder m is less than, equal to, or greater than half
-           of absy. However, we can't do that comparison directly because we
-           can't be sure that 0.5*absy is representable (the multiplication
-           might incur precision loss due to underflow). So instead we compare
-           m with the complement c = absy - m: m < 0.5*absy if and only if m <
-           c, and so on. The catch is that absy - m might also not be
-           representable, but it turns out that it doesn't matter:
-
-           - if m > 0.5*absy then absy - m is exactly representable, by
-             Sterbenz's lemma, so m > c
-           - if m == 0.5*absy then again absy - m is exactly representable
-             and m == c
-           - if m < 0.5*absy then either (i) 0.5*absy is exactly representable,
-             in which case 0.5*absy < absy - m, so 0.5*absy <= c and hence m <
-             c, or (ii) absy is tiny, either subnormal or in the lowest normal
-             binade. Then absy - m is exactly representable and again m < c.
-        */
-
-        c = absy - m;
-        if (m < c) {
-            r = m;
-        }
-        else if (m > c) {
-            r = -c;
-        }
-        else {
-            /*
-               Here absx is exactly halfway between two multiples of absy,
-               and we need to choose the even multiple. x now has the form
-
-                   absx = n * absy + m
-
-               for some integer n (recalling that m = 0.5*absy at this point).
-               If n is even we want to return m; if n is odd, we need to
-               return -m.
-
-               So
-
-                   0.5 * (absx - m) = (n/2) * absy
-
-               and now reducing modulo absy gives us:
-
-                                                  | m, if n is odd
-                   fmod(0.5 * (absx - m), absy) = |
-                                                  | 0, if n is even
-
-               Now m - 2.0 * fmod(...) gives the desired result: m
-               if n is even, -m if m is odd.
-
-               Note that all steps in fmod(0.5 * (absx - m), absy)
-               will be computed exactly, with no rounding error
-               introduced.
-            */
-            assert(m == c);
-            r = m - 2.0 * fmod(0.5 * (absx - m), absy);
-        }
-        return copysign(1.0, x) * r;
-    }
-
-    /* Special values. */
-    if (isnan(x)) {
-        return x;
-    }
-    if (isnan(y)) {
-        return y;
-    }
-    if (isinf(x)) {
-        return Py_NAN;
-    }
-    assert(isinf(y));
-    return x;
-}
-
-
 /*
     Various platforms (Solaris, OpenBSD) do nonstandard things for log(0),
     log(-ve), log(NaN).  Here are wrappers for log and log10 that deal with
@@ -1298,7 +1203,7 @@ FUNC1D(log1p, m_log1p, 0,
       "Return the natural logarithm of 1+x (base e).\n\n"
       "The result is computed in a way which is accurate for x near zero.",
       "expected argument value > -1, got %s")
-FUNC2(remainder, m_remainder,
+FUNC2(remainder, remainder,
       "remainder($module, x, y, /)\n--\n\n"
       "Difference between x and the closest integer multiple of y.\n\n"
       "Return x - n*y where n*y is the closest integer multiple of y.\n"