MATLAB: 1D to 2D interpolation

griddatainterpolationMATLAB

I would like to know how griddata operate. I would like to scatter 2D points to a 3D grid using the griddata interpolate. The code which brings some errors.
x=1:1:10;
y=11:1:20;
z= sqrt(x.^2+y.^2)
[xx,yy] = meshgrid(linspace(min(x),max(x),200),linspace(min(y),max(y),200))
zz=griddata(x,y,z,xx,yy,'nearest')
The error is as seen below.
Warning: The underlying triangulation is empty - the points may be collinear. 
> In griddata>useScatteredInterp (line 183)
In griddata (line 120) 
zz =
     []

Best Answer

In order for griddata to work meaningfully, the points xx,yy where you want to interpolate must be surrounded by scattered data points x,y (that's what "interpolation" means). Here, you have it the other way around.
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