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.
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SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001127s ]
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SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.001142s ]
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SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.001022s ]
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SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.019354s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001677s ]
UPDATE `jrk_articles` SET `hits` = 1 WHERE `id` = 25495 [ RunTime:0.001427s ]
