如何用matlab求函数最小值最大值啊？各位大侠，帮忙编一下这个函数的代码，谢谢啦！！！

Question

用matlab计算下面三个函数的最优解及其t的取值：
f1=686.4./t.^2.*(exp(0.3*t)-1)+1.31./t.*(exp(0.3*t)-0.3*t-1)+137.4./t.*(exp(0.3*t)-1)
f3=480-120./t-800./t.*(exp(0.3*t)-1)-355.6./t.*(exp(0.3*t)-0.3*t-1);
f2=480-240./t-843.97./t.*(exp(0.3*t)-1)-356./t.*(exp(0.3*t)-0.3*t-1)-219.6./t.^2.*(exp(0.3*t)-1)-146.528./t.^2.*(exp(0.3*t)-1).*(exp(-0.3*t)-1);
t的范围是大于等于零。
麻烦给出代码，谢谢啦！！急啊！！

Answer 1

举个例子
以第一个为例
syms t;
f1=686.4./t.^2.*(exp(0.3*t)-1)+1.31./t.*(exp(0.3*t)-0.3*t-1)+137.4./t.*(exp(0.3*t)-1);
df1=diff(f1,t)
tt=solve(df1,'t')
ezplot(f1)
minf=feval(@(t)eval(f1),tt)
hold on;
plot(tt,minf,'ro')
==========结果
df1 =

(131*((3*exp((3*t)/10))/10 - 3/10))/(100*t) + (2061*exp((3*t)/10))/(50*t) + (5148*exp((3*t)/10))/(25*t^2) - (687*(exp((3*t)/10) - 1))/(5*t^2) - (6864*(exp((3*t)/10) - 1))/(5*t^3) + (131*((3*t)/10 - exp((3*t)/10) + 1))/(100*t^2)

tt =

3.3907736905146573977514580257101

minf =

177.23480334269610970241980862625

Answer 2

#include<stdio.h>
int getMax(int a,int b,int c)
{
return a>b? a:(b>c? b:c);
}
int getMin(int a,int b,int c)
{
return a<b? a:(b<c? b:c);
}
void main()
{
int a,b,c;
printf("Please input three numbers:\n");
scanf("%d",&a);
scanf("%d",&b);
scanf("%d",&c);
printf("the max number is:%d\n",getMax(a,b,c));
printf("the min number is:%d\n",getMin(a,b,c));
getchar();
}

估计差不多，

追问

有错误
??? Error: File: Untitled3.m Line: 1 Column: 1
The input character is not valid in MATLAB statements or expressions.