# Using tabular data for Curve fitting of function z = f (x, y) with incomplete values of z. These blank z (i, j) automatically takes zero values and this is a problem

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Dear Community Members,

I have tabular data for data selection in the Curve fitter in the form of:.

I have to use curve fitter for z = f (x, y), but I don't have values for z(2, 4), z(3,3) and z(3,4) (red one).

In the workspase variable (matrix Z) these blank places automatically take values, which is zeros. Is there any instrument to ignore these zeros and the regression analyses to be made only with the available z values. In other words to ignore the three zero values in the down right corner? May be something with the weights instrument? If I simply use the matrix with zero values, without any additional actions, of course the regression method uses these z(2, 4) = 0, z(3,3) = 0 and z(3,4) = 0 and the results are unacceptable.

##### 2 Comments

Torsten
on 23 Sep 2024

### Accepted Answer

Torsten
on 25 Sep 2024

Edited: Torsten
on 25 Sep 2024

green = [5 5 5 5 5 4 4 4 4 1 1 1];

blue = [5 10 15 20 25 5 10 15 20 5 10 15];

yellow = [455 322 261 205 169 410 306 246 191 257 185 151];

F = @(p) fun(p,green,blue,yellow);

p0 = [1 1 1 1];

p = lsqnonlin(F,p0);

F(p)

norm(F(p))

a = p(1)

n = p(2)

b = p(3)

m = -p(4)/2

function res = fun(p,green,blue,yellow)

a = p(1);

n = p(2);

b = p(3);

m = p(4);

res = yellow - a*blue.^n.*((green+b).^2).^m;

end

##### 0 Comments

### More Answers (1)

Cris LaPierre
on 25 Sep 2024

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