Commit cfc21e2a authored by arjen@fred.bitbike.com's avatar arjen@fred.bitbike.com
Browse files

Arjen's LN()/LOG()/LOG2() extensions into manual (with improvements).

parent 97a62ca4

Docs/manual.texi

+56 −3
Original line number Diff line number Diff line
@@ -32160,17 +32160,58 @@ mysql> SELECT EXP(2); 
mysql> SELECT EXP(-2);

        -> 0.135335

@end example













@findex LN()













@item LN(X)













Returns the natural logarithm of @code{X}:













@example













mysql> SELECT LN(2);













        -> 0.693147













mysql> SELECT LN(-2);













        -> NULL













@end example

























This function was added in MySQL version 4.0.3.













It is synonymous with @code{LOG(X)} in MySQL.



























@findex LOG()















@item LOG(X)













Returns the natural logarithm of @code{X}:













@itemx LOG(B,X)













If called with one parameter, this function returns the natural logarithm













of @code{X}:















@example















mysql> SELECT LOG(2);















        -> 0.693147















mysql> SELECT LOG(-2);















        -> NULL















@end example













If you want the log of a number @code{X} to some arbitrary base @code{B}, use













the formula @code{LOG(X)/LOG(B)}.

























If called with two parameters, this function returns the logarithm of













@code{X} for an arbitary base @code{B}:













@example













mysql> SELECT LOG(2,65536);













        -> 16.000000













mysql> SELECT LOG(1,100);













        -> NULL













@end example

























The arbitrary base option was added in MySQL version 4.0.3.













@code{LOG(B,X)} is equivalent to @code{LOG(X)/LOG(B)}.

























@findex LOG2()













@item LOG2(X)













Returns the base-2 logarithm of @code{X}:













@example













mysql> SELECT LOG2(65536);













        -> 16.000000













mysql> SELECT LOG2(-100);













        -> NULL













@end example

























@code{LOG2()} is useful for finding out how many bits a number would













require for storage.













This function was added in MySQL version 4.0.3.













In earlier versions, you can use @code{LOG(X)/LOG(2)} instead.





























@findex LOG10()















@item LOG10(X)










@@ -50020,6 +50061,7 @@ Our TODO section contains what we plan to have in 4.0. @xref{TODO MySQL 4.0}.



























@node News-4.0.3, News-4.0.2, News-4.0.x, News-4.0.x















@appendixsubsec Changes in release 4.0.3



























@itemize @bullet















@item















Allow @code{DEFAULT} with @code{INSERT} statement.










@@ -50056,8 +50098,19 @@ Fixed a bug that made the pager option in the @code{mysql} client













non-functional.















@item















Added full @code{AUTO_INCREMENT} support to @code{MERGE} tables.













@item













Extended @code{LOG()} function to accept an optional arbitrary base













parameter.













@xref{Mathematical functions}.













@item













Added @code{LOG2()} function (useful for finding out how many bits













a number would require for storage).













@item













Added @code{LN()} natural logarithm function for compatibility with













other databases. It is synonymous with @code{LOG(X)}.















@end itemize









































@node News-4.0.2, News-4.0.1, News-4.0.3, News-4.0.x















@appendixsubsec Changes in release 4.0.2 (01 July 2002)