function F = myfunn(beta,x)
F=((beta(1)*x(:,1)-beta(2)*x(:,2)).^4+beta(3)*(x(:,1)-x(:,2))).^0.25-273.15;
命令行輸入：
x=[132.4,148.5,171.1,193,219.2,245.7,273.8,304.3]';
y=[62.4,69.1,77.2,85,93.4,102.1,113.9,126.6]';
z=[1000,1050,1100,1150,1200,1250,1300,1350]';
x=[x y];
beta=nlinfit(x,z,@myfunn,[10 10 10])