You are viewing a plain text version of this content. The canonical link for it is here.
Posted to issues@spark.apache.org by "Kazuyuki Tanimura (Jira)" <ji...@apache.org> on 2023/11/04 00:36:00 UTC
[jira] [Created] (SPARK-45786) Inaccurate Decimal multiplication and division results
Kazuyuki Tanimura created SPARK-45786:
-----------------------------------------
Summary: Inaccurate Decimal multiplication and division results
Key: SPARK-45786
URL: https://issues.apache.org/jira/browse/SPARK-45786
Project: Spark
Issue Type: Bug
Components: SQL
Affects Versions: 3.5.0, 3.4.1, 3.3.3, 3.2.4
Reporter: Kazuyuki Tanimura
Decimal multiplication and division results may be inaccurate due to rounding issues.
h2. Multiplication:
{code:scala}
scala> sql("select -14120025096157587712113961295153.858047 * -0.4652").show(truncate=false)
+----------------------------------------------------+
|(-14120025096157587712113961295153.858047 * -0.4652)|
+----------------------------------------------------+
|6568635674732509803675414794505.574764 |
+----------------------------------------------------+
{code}
The correct answer is
{quote}6568635674732509803675414794505.574763
{quote}
Please note that the last digit is 3 instead of 4 as
{code:scala}
scala> java.math.BigDecimal("-14120025096157587712113961295153.858047").multiply(java.math.BigDecimal("-0.4652"))
val res21: java.math.BigDecimal = 6568635674732509803675414794505.5747634644
{code}
Since the factional part .574763 is followed by 4644, it should not be rounded up.
h2. Division:
{code:scala}
scala> sql("select -0.172787979 / 533704665545018957788294905796.5").show(truncate=false)
+-------------------------------------------------+
|(-0.172787979 / 533704665545018957788294905796.5)|
+-------------------------------------------------+
|-3.237521E-31 |
+-------------------------------------------------+
{code}
The correct answer is
{quote}-3.237520E-31
{quote}
Please note that the last digit is 0 instead of 1 as
{code:scala}
scala> java.math.BigDecimal("-0.172787979").divide(java.math.BigDecimal("533704665545018957788294905796.5"), 100, java.math.RoundingMode.DOWN)
val res22: java.math.BigDecimal = -3.237520489418037889998826491401059986665344697406144511563561222578738E-31
{code}
Since the factional part .237520 is followed by 4894..., it should not be rounded up.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@spark.apache.org
For additional commands, e-mail: issues-help@spark.apache.org