do you mean this:
close all
clear,clc
x=[0 -1.73205161513813 -1.73210161662818
0 -1.73205161513813 0
0 -1.73205161513813 1.73210161662818
0 0 -1.73210161662818
0 0 0
0 0 1.73210161662818
0 1.73205161513813 -1.73210161662818
0 1.73205161513813 0
0 1.73205161513813 1.73210161662818
1.73210161662818 -1.73205161513813 -1.73210161662818
1.73210161662818 -1.73205161513813 0
1.73210161662818 -1.73205161513813 1.73210161662818
1.73210161662818 0 -1.73210161662818
1.73210161662818 0 0
1.73210161662818 0 1.73210161662818
1.73210161662818 1.73205161513813 -1.73210161662818
1.73210161662818 1.73205161513813 0
1.73210161662818 1.73205161513813 1.73210161662818
-1.73210161662818 -1.73205161513813 -1.73210161662818
-1.73210161662818 -1.73205161513813 0
-1.73210161662818 -1.73205161513813 1.73210161662818
-1.73210161662818 0 -1.73210161662818
-1.73210161662818 0 0
-1.73210161662818 0 1.73210161662818
-1.73210161662818 1.73205161513813 -1.73210161662818
-1.73210161662818 1.73205161513813 0
-1.73210161662818 1.73205161513813 1.73210161662818];
[x1,x2,x3]=deal(x(:,1),x(:,2),x(:,3));
x1fit = min(x1):.1:max(x1);
x2fit = min(x2):.1:max(x2);
x3fit = min(x3):.1:max(x3);
[X1FIT,X2FIT] = meshgrid(x1fit,x2fit);
X3FIT=griddata(x1fit,x2fit,x3fit,X1FIT,X2FIT,'v4');
b=[898.619500324491 -49.6569643950741 0.957244154182521 -0.474633267533362 0.109261217410249 0.128653191020651 0.109267525885722 0.0654684323159314 0.155519747861591 -0.265812849175710];
YFIT = b(1)+b(2)*X1FIT+b(3)*X2FIT+b(4)*X3FIT+b(5)*(X1FIT.^2-1)+b(6)*X1FIT.*X2FIT+b(7)*(X2FIT.^2-1)+b(8)*X2FIT.*X3FIT+b(9)*(X3FIT.^2-1)+b(10)*X3FIT.*X1FIT;
surf(X1FIT,X2FIT,X3FIT,YFIT)
Best Answer