完成DCT变换，可以对多维数据进行操作
输入数据可以是数值类型也可以是逻辑类型，输出数据时双精度类型
参考文献： Narasimha M. et al, On the computation of the discrete cosine transform, IEEE Trans Comm, 26, 6, 1978, pp 934-936.
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.000987s ]
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:0.075605s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001068s ]
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SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.001022s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003385s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.000827s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.004068s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.013988s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001411s ]
UPDATE `jrk_articles` SET `hits` = 2 WHERE `id` = 25495 [ RunTime:0.018171s ]
