多项式指数函数的 单调不减 如何用代码定义

是 否 +2 论坛币

k人 参与回答

经管之家送您一份

应届毕业生专属福利!

求职就业群

赵安豆老师微信：zhaoandou666

经管之家联合CDA

送您一个全额奖学金名额~ !

立即领取

感谢您参与论坛问题回答

经管之家送您两个论坛币！

+2 论坛币

x=[0 29 64 92 123 154 200 244 278 313 338 367 397];
y=[0 14 18 29 46 88 148 199 213 221 233 236 237];

y=exp(b0+b1*x+b2*x.^2+b3*x.^3+b4*x.^4)     %函数式，系数是待求的对象

x代表累计的天数，y代表累计结果。如，第367观察到的累计结果236，第397天观察到的沉降总量为237。x可无限增大，但y值到一定程度就不再增加，但是绝不会减少（x和y都是累计数）。如何通过  matlab 代码， 限定该函数的 “单调不减” 性？恳请结合本数据，给个具体代码。我是文科生，不懂高数。

恳请先哲恩赐

叩首躬谢

扫码加我 拉你入群

请注明：姓名-公司-职位

以便审核进群资格，未注明则拒绝

分享0 收藏0 回帖

关键词：多项式 如何用 MATLAB atlab matla matlab 回归

you may add a constraint on those parameters, thus the derivative dy/dx is positive all the time, namely, you would solve for those b's with an extra condition that (b1+2*b2*x+3*b3*x^2+4*b4*x^3) >=0 for all x.
you may still end up with many solutions, so you may need other additional conditions if you're asking for a unique solution.

Many thanks for your kindness. Could you please offer a code so that I can copy and run it? I am a green hand, you know.
Best regards

Sorry i don't program in Matlab. btw, i don't think exp() is a good fit to your data. y=log(polynomial(x)) could be a candidate since it saturates when x is large.

点个赞加点人气
感谢分享