Mercurial > cpython-lru_cache-weakref

diff Python/bltinmodule.c @ 57164:bca027b6df53 2.6

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Issue #7070: Fix problem with builtin round function for large odd integer arguments. Also fixes the sign of round(-0.0).
author Mark Dickinson <dickinsm@gmail.com>
date Mon, 09 Nov 2009 17:45:40 +0000
parents f65d62473465
children 2628216bc66d
line wrap: on
line diff
--- a/Python/bltinmodule.c	Mon Nov 09 16:47:50 2009 +0000
+++ b/Python/bltinmodule.c	Mon Nov 09 17:45:40 2009 +0000
@@ -2120,7 +2120,7 @@
 static PyObject *
 builtin_round(PyObject *self, PyObject *args, PyObject *kwds)
 {
-	double number;
+	double number, abs_number, abs_result;
 	double f;
 	int ndigits = 0;
 	int i;
@@ -2137,10 +2137,14 @@
 		number /= f;
 	else
 		number *= f;
-	if (number >= 0.0)
-		number = floor(number + 0.5);
-	else
-		number = ceil(number - 0.5);
+
+	/* round `number` to nearest integer, rounding halves away from zero */
+	abs_number = fabs(number);
+	abs_result = floor(abs_number);
+	if (abs_number - abs_result >= 0.5)
+		abs_result += 1.0;
+	number = copysign(abs_result, number);
+
 	if (ndigits < 0)
 		number *= f;
 	else