用FUNCTION搞定，怎么定义多元的如：y=x1*x2/x3？

Question

MATLAB运用优化工具解决问题时，怎么定义多元函数。一元的：function=文件名（x）；y=2*x^2;..其中有要确定目标函数的么，用FUNCTION搞定，怎么定义多元的如：y=x1*x2/x3菜鸟求助，问题白痴，多多包涵

Answer 1

如果是多元函数的话，可以参考fminseach
Example 1

The Rosenbrock banana function is a classic test example for multidimensional minimization:
f=x(1)^2+a*x(2)^2; 目标函数 
The minimum is at (1,1) and has the value 0. The traditional starting point is (-1.2,1). The anonymous function shown here defines the function and returns a function handle called banana:
function f=myfun(x,a) 新建着这样的M文件
banana = @(x)100*(x(2)-x(1)^2)^2+(1-x(1))^2;

Pass the function handle to fminsearch:

[x,fval] = fminsearch(banana,[-1.2, 1])  
用这样的格式条用fminseach以及M函数， 其中[-1.2,1]为优化其实点

This produces 运行以后的结果

x =

1.0000 1.0000

fval = 这个是优化点的函数值

8.1777e-010

This indicates that the minimizer was found to at least four decimal places with a value near zero.