f[Subscript[w, j]] = 1/2 \!\(\*UnderoverscriptBox[\(\[Sum]\), \(i = 1\), \(n\)]\*SuperscriptBox[\((\*UnderoverscriptBox[\(\[Sum]\), \(j = 0\), \(m\)]\*SubscriptBox[\(w\), \(j\)] \*SubsuperscriptBox[\(x\), \(i\), \(j\)] - \*SubscriptBox[\(y\), \(i\)])\), \(2\)]\)

L := proc (w__j) options operator, arrow; (1/2)*(sum((sum(w__j*x__i^j, j = 0 .. m)-y__i)^2, i = 1 .. n)) end proc

6楼: Originally posted by wurongjun at 2016-01-08 12:48:53
你用Matlab多好啊!
就一个命令而已:
polyfit(x,y,M)

2楼: Originally posted by 赵梦92 at 2016-01-08 12:31:47
大前提错了吧。我的书上和你的不一样呢