function instead of grid data without Interpolation

I want to make Matrix with 3 vector. but griddata make wrong result, does any one know the other function for making matrix?

[madhan ravi]

Could you upload the code so that the pattern is observed and an alternative solution can be given?

[Mah Mhata]

clear all
close all
clc
x=[1,8,2,8];
y=[2,3,0,9];
z=[80,30,30,40];
[X,Y]=meshgrid(x,y)
Z=griddata(x,y,z,X,Y)
u=trapz(x,Z,2)
I=trapz(y,u)

Answer 1

[KSSV]

x=[1,8,2,8];
y=[2,3,0,9];
z=[80,30,30,40];
[X,Y]=meshgrid(x,y) ;

F = scatteredInterpolant(x',y',z') ;
Z = F(X,Y) ;
u=trapz(x,Z,2)
I=trapz(y,u)

[madhan ravi]

Was thinking the same but https://www.mathworks.com/help/matlab/ref/scatteredinterpolant.html interpolates data right kssv? asking out of curiosity because your an expert in this.

[KSSV]

Yes it interpolates the scattered data.

[madhan ravi]

It was confusing because OP mentioned "function instead of grid data without Interpolation" so I thought there is some function which doesn't interpolate data similar to griddata() or scatteredInterpolant()?

[Mah Mhata]

Z =

80.0000 25.0771 70.0000 25.0771

91.7930 30.0000 74.2857 30.0000

40.5238 8.7696 30.0000 8.7696

129.8353 40.0000 112.3279 40.0000

It has interpolation too.It is not right answer for calculating the area under this curve.

what should I do?I think my data is in 3d model, please help me how I can calculate the area under the curve or surface