[slgu]

该y只与x1, x2有关，与其它x无关，清运行下列以小程序：
clear,clc
x1=[3624.1, 4038.2, 4517.8, 4860.3, 5301.8, 5957.1, 7206.7, 8989.1, 10201.4, 11954.5, 14922.3, 16917.8, 18598.4, 21662.5, 26651.9, 34650.5, 46532.9, 57277.3]';
x2=[519.28, 537.82, 571.7, 629.89, 700.02, 755.59, 947.35, 2040.79, 2090.73, 2140.36, 2390.47, 2727.4, 2821.87, 2990.17, 3296.91, 4255.3, 5126.88, 6038.04]';
y=[1132.62, 1146.38, 1159.93, 1175.79, 1212.33, 1866.95, 1642.86, 2004.82, 2122.01, 2199.35, 2357.24, 2664.9, 2937.1, 3149.48, 3483.37, 4348.95, 5218.1, 6242.2]';
n=size(y,1);
X=[ones(n,1),x1,x2];
str=num2str([1:n]');ry=range(y);
b=X\y
fx=@(b,x1,x2)b(1)+b(2)*x1+b(3)*x2;
figure(1)
clf
plot3(x1,x2,y,'o')
stem3(x1,x2,y,'filled')
text(x1,x2,y+ry/50,str,'fontsize',14)
hold on
[x11,x22]=meshgrid(min(x1):range(x2)/80:max(x1),min(x2):range(x2)/80:max(x2));
y1=fx(b,x11,x22);
surf(x11,x22,y1);
shading interp
alpha(.8)
axis tight