应用离散傅里叶变换DFT，通过MATLAB实现对连续信号频谱分析，以满足理论分析和工程实际的需要。
-application DFT Discrete Fourier Transform, right through MATLAB continuous signal spectrum analysis, in order to meet the theoretical analysis and practical needs.
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.001379s ]
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:0.096147s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001232s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001906s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.001307s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003597s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.001065s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003207s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.014894s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001360s ]
UPDATE `jrk_articles` SET `hits` = 1 WHERE `id` = 26980 [ RunTime:0.001403s ]
