find minimum of function with four variables using simplex search method of nelder and mead

Question

Saqib Zafar 2021-5-26

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/839860-find-minimum-of-function-with-four-variables-using-simplex-search-method-of-nelder-and-mead

评论： Star Strider 2021-5-26

在 MATLAB Online 中打开

Hi community. Please help me. Following is the code I have written, but it does not work and is showing an error.

Failure in initial objective function evaluation. FMINUNC cannot continue.

My code is:

close all; clc; clear all;
syms p1 p2 
f=@(D) 0.008*D^-1/3
Q=@(p1,p2,D,L)3.39*(((p1^2-p2^2)*D^5)/f*L)^1/2==100*10^6/24;
p1=solve(Q,p1)
r=p1/p2;
f=@(D,p1,L,r) 7.84*D.^2*p1+450000+36900*D+6.57*10.^6/L+(772*10.^6/L)*(r.^0.219-1)
x0=[1 1];
[x_MIN,f_MIN]=fminunc(f,x0)
f=@(D,p1,L,r) -(7.84*D.^2*p1+450000+36900*D+6.57*10.^6/L+(772*10.^6/L)*(r.^0.219-1));
x0=[-1 -1];
[x_MAX,f_MAX]=fminunc(f,x0)