[jira] [Commented] (FLINK-6891) Add LOG(X) supported in SQL

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-6891?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16077469#comment-16077469 ] 

ASF GitHub Bot commented on FLINK-6891:
---------------------------------------

Github user sunjincheng121 commented on the issue:

    https://github.com/apache/flink/pull/4122
  
     I have rebase the code and update the PR. 


> Add LOG(X) supported in SQL
> ---------------------------
>
>                 Key: FLINK-6891
>                 URL: https://issues.apache.org/jira/browse/FLINK-6891
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Table API & SQL
>    Affects Versions: 1.4.0
>            Reporter: sunjincheng
>            Assignee: sunjincheng
>
> LOG(X), LOG(B,X)
> If called with one parameter, this function returns the natural logarithm of X. If X is less than or equal to 0.0E0, the function returns NULL and (as of MySQL 5.7.4) a warning “Invalid argument for logarithm” is reported.
> The inverse of this function (when called with a single argument) is the EXP() function.
> If called with two parameters, this function returns the logarithm of X to the base B. If X is less than or equal to 0, or if B is less than or equal to 1, then NULL is returned.
> * Example:
>  LOG(2) -> 0.69314718055995
>  LOG(-2) -> NULL
>  LOG(2,65536) -> 16
>  LOG(10,100) -> 2
>  LOG(1,100) -> NULL
> * See more:
> ** [MySQL| https://dev.mysql.com/doc/refman/5.7/en/mathematical-functions.html#function_log]
> --NOTE-- In this JIRA. NULL case will throw IllegalArgumentException.



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