代数方法的 圆拟合代码，无拟合偏差！参数含有如下：
%
% Input: XY(n,2) is the array of coordinates of n points x(i)=XY(i,1), y(i)=XY(i,2)
%
% Output: Par = [a b R] is the fitting circle:
% center (a,b) and radius R
SHOW FULL COLUMNS FROM `jrk_downrecords` [ RunTime:0.001282s ]
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:0.092837s ]
SHOW FULL COLUMNS FROM `jrk_tagrecords` [ RunTime:0.001229s ]
SELECT * FROM `jrk_tagrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 20 [ RunTime:0.001904s ]
SHOW FULL COLUMNS FROM `jrk_member` [ RunTime:0.001235s ]
SELECT `id`,`username`,`userhead`,`usertime` FROM `jrk_member` WHERE `status` = 1 ORDER BY `usertime` DESC LIMIT 10 [ RunTime:0.003613s ]
SHOW FULL COLUMNS FROM `jrk_searchrecords` [ RunTime:0.001131s ]
SELECT * FROM `jrk_searchrecords` WHERE `status` = 1 ORDER BY `num` DESC LIMIT 5 [ RunTime:0.003326s ]
SELECT aid,title,count(aid) as c FROM `jrk_downrecords` GROUP BY `aid` ORDER BY `c` DESC LIMIT 10 [ RunTime:0.016403s ]
SHOW FULL COLUMNS FROM `jrk_articles` [ RunTime:0.001553s ]
UPDATE `jrk_articles` SET `hits` = 1 WHERE `id` = 33174 [ RunTime:0.001610s ]
