How to interpolate only on a certain direction?

Hello, I have a series of matrix H of dimensions: 2x2x2049, defined for 2049 values of the frequency, from 0 to 3200 Hz. I would interpolate H so that I will have a series of matrix of dimensions 2x2x100000 for 100000 values of the frequency, from 5 to 50 Hz. How can I do this?

[Adam]

doc interp3

should work for this, provided you give it the same input and output grids for the first two dimensions.

[Alessandro Longo]

It does not work. I tried in this way:

 [xx,yy,zz] = meshgrid(1:2,1:2,f_swept);
 Htrue_interp = interp3(Htrue,xx,yy,zz,'spline');

where Htrue has dimension 2x2x2049 and f_swept is my long vector

Answer 1

[Matt J]

Hr=reshape(  permute(H,[3,1,2]) , [],4 );  %convert to 2D array

     tmp=interp1(...,Hr,...);  %interpolate the columns

Hnew= reshape( ipermute(tmp,[3,1,2])   ,[2,2,100000] );  %convert back to 3D

[Alessandro Longo]

It does not work

[Matt J]

Yes it does...

[Matt J]

Take this H as a simpler example

        H(:,:,1) =

           1     1
           1     1

      H(:,:,2) =

           2     2
           2     2

      H(:,:,3) =

           3     3
           3     3

I will upsample it by a factor 2 by interpolation:

tmp=interp1(Hr,linspace(1,3,5)); 
Hnew= reshape( ipermute(tmp,[3,1,2])   ,[2,2,5] );

The result:

        Hnew(:,:,1) =

           1     1
           1     1

      Hnew(:,:,2) =

          1.5000    1.5000
          1.5000    1.5000

      Hnew(:,:,3) =

           2     2
           2     2

      Hnew(:,:,4) =

          2.5000    2.5000
          2.5000    2.5000

      Hnew(:,:,5) =

           3     3
           3     3

Is this not the kind of thing you want???