Surface fitting problem

[brunoserrano]

Hi have problem when doing surface fitting the surface that i obtained has the x and y axis switched. The code is:

ft = fittype( 'poly33' );
opts = fitoptions( ft );
opts.Weights = zeros(1,0);
coeffnames(ft) %mostra os coeficientes

formula(ft) %mostra a equação final


c = fit( [xi, yi], zi, ft, opts )

coef = coeffvalues(c)

figure( 'Name', 'Surface fitting' );
h=plot( c, [xi, yi], zi );

And when i going to cheek the surface it apperes that x and y are exchanged.

figure
step_x=(2*(a+a_i*1/4+a/10))/50;
step_y=0.007/50;

for i=1:50+1
x_v(i,1)=-a-a_i*1/4-a/10+step_x*(i-1);
y_v(i,1)=step_y*(i-1);
end

clear x y
for i=1:50+1
for j=1:50+1
x=x_v(i,1);
y=y_v(j,1);
Z(i,j)=coef(1,1) + coef(1,2)*x + coef(1,3)*y + coef(1,4)*x^2 + coef(1,5)*x*y + coef(1,6)*y^2 + ...
coef(1,7)*x^3 + coef(1,8)*y*x^2 + coef(1,9)*x*y^2 + coef(1,10)*y^3;
end
end

surf(x_v,1),y_v,1),Z,)

Thanks!