atan函数，由于在通信系统中很多信息都是依赖相位信息得到，所以atan函数非常有用。-atan function, because a lot of information communication systems, which rely on phase information is therefore very useful function atan.
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.001943s ]
SELECT `a`.`aid`,`a`.`title`,`a`.`create_time`,`m`.`username` FROM `jrk_downrecords` `a` INNER JOIN `jrk_member` `m` ON `a`.`uid`=`m`.`id` WHERE `a`.`status` = 1 GROUP BY `a`.`aid` ORDER BY `a`.`create_time` DESC LIMIT 10 [ RunTime:0.155275s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001338s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001978s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.001415s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003676s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.001140s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003214s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.014828s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001580s ]
UPDATE `jrk_articles` SET `hits` = 1 WHERE `id` = 123178 [ RunTime:0.001230s ]
