Make to_numeric default to correct precision

doc/source/whatsnew/v1.1.2.rst

@@ -37,6 +37,7 @@ Bug fixes
 - Bug in :meth:`Series.dt.isocalendar` and :meth:`DatetimeIndex.isocalendar` that returned incorrect year for certain dates (:issue:`36032`)
 - Bug in :class:`DataFrame` indexing returning an incorrect :class:`Series` in some cases when the series has been altered and a cache not invalidated (:issue:`33675`)
 - Bug in :meth:`DataFrame.corr` causing subsequent indexing lookups to be incorrect (:issue:`35882`)
+- Bug in :func:`to_numeric` where precision was incorrect (:issue:`31364`)
 
 .. ---------------------------------------------------------------------------
 

pandas/_libs/src/parse_helper.h

@@ -18,7 +18,9 @@ int to_double(char *item, double *p_value, char sci, char decimal,
     char *p_end = NULL;
     int error = 0;
 
-    *p_value = xstrtod(item, &p_end, decimal, sci, '\0', 1, &error, maybe_int);
+    /* Switch to precise xstrtod GH 31364 */
+    *p_value = precise_xstrtod(item, &p_end, decimal, sci, '\0', 1,
+                               &error, maybe_int);
 
     return (error == 0) && (!*p_end);
 }

pandas/tests/tools/test_to_numeric.py

@@ -649,3 +649,10 @@ def test_failure_to_convert_uint64_string_to_NaN():
     ser = Series([32, 64, np.nan])
     result = to_numeric(pd.Series(["32", "64", "uint64"]), errors="coerce")
     tm.assert_series_equal(result, ser)
+
+
+def test_precision():
+    # GH 31364
+    result = to_numeric("243.164")
+
+    assert result == 243.164