Produce and play a sound signal of 6 seconds f(t)=exp(t-6)sin(2π*Ft) with a sampling rate of 8000dots/s by using MATLAB, with the frequency F being 494, 440, 392, 440, 494 and 494 Hz in order. Each frequency should last for 1 second.
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.001039s ]
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:0.075329s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.000994s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001290s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.000981s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003270s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.001040s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003966s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.017910s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.017854s ]
UPDATE `jrk_articles` SET `hits` = 2 WHERE `id` = 85550 [ RunTime:0.025786s ]
