function createFit
%% Fit: 'untitled fit 1'.
x=[200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600,200,400,600,800,1000,1200,1400,1600,1800,2000,2200,2400,2600];
y=[1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,9,9,9,9,9,9,9,9,9,9,9,9,9,10,10,10,10,10,10,10,10,10,10,10,10,10,20,20,20,20,20,20,20,20,20,20,20,20,20,40,40,40,40,40,40,40,40,40,40,40,40,40,60,60,60,60,60,60,60,60,60,60,60,60,60,80,80,80,80,80,80,80,80,80,80,80,80,80,100,100,100,100,100,100,100,100,100,100,100,100,100,200,200,200,200,200,200,200,200,200,200,200,200,200,300,300,300,300,300,300,300,300,300,300,300,300,300,400,400,400,400,400,400,400,400,400,400,400,400,400,500,500,500,500,500,500,500,500,500,500,500,500,500,600,600,600,600,600,600,600,600,600,600,600,600,600,700,700,700,700,700,700,700,700,700,700,700,700,700,800,800,800,800,800,800,800,800,800,800,800,800,800,900,900,900,900,900,900,900,900,900,900,900,900,900,1000,1000,1000,1000,1000,1000,1000,1000,1000,1000,1000,1000,1000,1100,1100,1100,1100,1100,1100,1100,1100,1100,1100,1100,1100,1100,1300,1300,1300,1300,1300,1300,1300,1300,1300,1300,1300,1300,1300];
z=[1.87580000000000e-17,0.00476020000000000,188.730000000000,22193,259810,1003400,2117200,3170300,3926800,4329700,4422000,4394600,4324800,2.24080000000000e-17,0.00682410000000000,306.660000000000,38782,475190,1890900,4071600,6181400,7727800,8573200,8790400,8757600,8631400,2.63200000000000e-17,0.0123540000000000,759.010000000000,116910,1629300,7074600,16180000,25617000,32964000,37292000,38732000,38908000,38546000,2.64820000000000e-17,0.0127590000000000,802.380000000000,125550,1768300,7734400,17781000,28253000,36449000,41306000,42951000,43179000,42796000,2.72790000000000e-17,0.0153350000000000,1125.80000000000,196420,2981400,13739000,32779000,53475000,70280000,80676000,84621000,85555000,85107000,2.77340000000000e-17,0.0176120000000000,1507,295630,4877600,23858000,59413000,99971000,134320000,156600000,166020000,169050000,168940000,1200900000.00000,0.0187460000000000,1748.60000000000,368470,6407800,32566000,83395000,143210000,195280000,230060000,245670000,251390000,252040000,2.79810000000000e-17,0.0194510000000000,1924.50000000000,427030,7721200,40381000,105620000,184200000,254030000,301720000,324030000,332850000,334570000,2.80330000000000e-17,0.0199400000000000,2061.70000000000,476340,8884500,47552000,126510000,223470000,311070000,371940000,401320000,413580000,416630000,2.81380000000000e-17,0.0211510000000000,2479.20000000000,649630,13400000,77423000,218200000,402340000,578160000,707520000,776160000,809160000,821520000,2.81730000000000e-17,0.0216620000000000,2707.20000000000,762810,16730000,101400000,296440000,562060000,824710000,1024900000.00000,1137100000.00000,1194700000.00000,1219600000.00000,2.81910000000000e-17,0.0219500000000000,2857.60000000000,846840,19412000,121900000,366250000,709100000,1057100000.00000,1329400000.00000,1487600000.00000,1572800000.00000,1612400000.00000,2.82020000000000e-17,0.0221380000000000,2966.80000000000,913370,21676000,139980000,429940000,846660000,1278700000.00000,1623600000.00000,1829900000.00000,1944700000.00000,2000900000.00000,2.82090000000000e-17,0.0222690000000000,3050.50000000000,968200,23640000,156270000,488900000,976670000,1491200000.00000,1909400000.00000,2165200000.00000,2311400000.00000,2385700000.00000,2.82150000000000e-17,0.0223660000000000,3117.30000000000,1014600,25375000,171140000,544030000,1100400000.00000,1696400000.00000,2187900000.00000,2494500000.00000,2673400000.00000,2767200000.00000,2.82190000000000e-17,0.0224420000000000,3172.20000000000,1054700,26935000,184860000,595960000,1218800000.00000,1895000000.00000,2460000000.00000,2818300000.00000,3031100000.00000,3145500000.00000,2.82220000000000e-17,0.0225020000000000,3218.20000000000,1089900,28348000,197630000,645160000,1332500000.00000,2087200000.00000,2726400000.00000,3137300000.00000,3385100000.00000,3521000000.00000,2.82240000000000e-17,0.0225510000000000,3257.50000000000,1121300,29643000,209570000,691980000,1442200000.00000,2275500000.00000,2987600000.00000,3451800000.00000,3735700000.00000,3894000000.00000,2.82260000000000e-17,0.0225920000000000,3291.40000000000,1149200,30835000,220810000,736730000,1548300000.00000,2458600000.00000,3244000000.00000,3762300000.00000,4082900000.00000,4264500000.00000,2.82290000000000e-17,0.0226570000000000,3347.50000000000,1197700,32974000,241510000,820830000,1750600000.00000,2812400000.00000,3744200000.00000,4371900000.00000,4768500000.00000,4998900000.00000];
[xData, yData, zData] = prepareSurfaceData( x, y, z );
% Set up fittype and options.
ft = fittype( 'a*y*^b*exp(-c/x)', 'independent', {'x', 'y'}, 'dependent', 'z' );
opts = fitoptions( 'Method', 'NonlinearLeastSquares' );
opts.Display = 'Off';
opts.StartPoint = [380000000 0.9064 9532];
% Fit model to data.
[fitresult, gof] = fit( [xData, yData], zData, ft, opts );
% Plot fit with data.
figure( 'Name', 'untitled fit 1' );
h = plot( fitresult, [xData, yData], zData );
legend( h, 'untitled fit 1', 'z vs. x, y', 'Location', 'NorthEast' );
% Label axes
xlabel x
ylabel y
zlabel z
grid on
上述中，红色标记部分x,y,z是我的原始数据，蓝色标记部分是我要拟合的表达式以及a,b,c三个参数的初值，我要实现的目的是把拟合出来的三维曲面跟我的原始数据点放到一个图上，但是函数总是定义不了，谢谢了