Matt P created CALCITE-5182:
-------------------------------
Summary: STDDEV returning NaN values
Key: CALCITE-5182
URL: https://issues.apache.org/jira/browse/CALCITE-5182
Project: Calcite
Issue Type: Bug
Reporter: Matt P
Example w/ Calcite 1.30:
{code:java}
0: jdbc:calcite:model=src/test/resources/mode> SELECT STDDEV(x) FROM (VALUES
1+power(2,-52), 1+power(2,-51)) x;
+--------+
| EXPR$0 |
+--------+
| NaN |
+--------+
1 row selected (0.577 seconds){code}
{{{}{}}}This is due to the numerical issues in the formula that is being used:
{code:java}
variance = avg(x*x) - avg(x)*avg(x){code}
Though mathematically this should always be non-negative, due to numerical
errors it can be negative and thus when the square root is taken to get the
STDDEV it results in NaN.
--
This message was sent by Atlassian Jira
(v8.20.7#820007)
