×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# Surface fitting problem

## Surface fitting problem

(OP)
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!

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!