I got this error : Error using fit>iFit (line 139) Y must be a column vector. Error in fit (line 116) [fitobj, goodness, output, convmsg] = iFit( xdatain, ydatain, fittypeobj, ... Error in c (line 13) surfacefit(x,y)=fit([x, y],z,'poly33')

image_data =dicomread('image.dcm');

imag=image_data(:,:,42), [];

imshow(imag);

ima=imnormalize( imag, 0,1)

[x, y] = find(ima)

z=ima(y,x)

%x=reshape(x,[],1)

%y=reshape(y,[],1)

surfacefit=fit([x, y],z,'poly33')

plot(surfacefit,[x,y],z)

How to surface fit the segmented image? where x and y coordinates-pixel coordinates

z coordinate-intensity