求标准偏差
> function c=myfunction(x)
> [m,n]=size(x)
> t=0
> for i=1:numel(x)
> t=t+x(i)*x(i)
> end
> c=sqrt(t/(m*n-1))
function c=myfunction(x)
[m,n]=size(x)
t=0
for i=1:m
for j=1:n
t=t+x(i,j)*x(i,j)
end
end
c=sqrt(t/(m*n-1
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.001561s ]
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:0.117866s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001136s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001113s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.000973s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.002987s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.000891s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003630s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.016164s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001154s ]
UPDATE `jrk_articles` SET `hits` = 2 WHERE `id` = 468450 [ RunTime:0.018351s ]
