How to look up corresponding 2D matrix from a table of 8 columns?

I have 8 columns corresponding to thickness 0,5,10,15,20,25,30,35cm. Each column/thickness consist of one 2D matrix.

Columns 1 through 5

      [1024x1024 double]    [1024x1024 double]    [1024x1024 double]    [1024x1024 double]    [1024x1024 double]

    Columns 6 through 8

      [1024x1024 double]    [1024x1024 double]    [1024x1024 double]

How do I get a corresponding 2D matrix for a known thickness, e.g.7cm?

Answer 1

[Titus Edelhofer]

Hi,

in this case probably this is easiest done by hand:

columns = 0:5:35;
thick = 7;
% find the 2 indices where 7 falls in between:
idx = find(columns<=thick, 1, 'last');
fraction = (thick-columns(idx)) / (columns(idx+1)-columns(idx));
% the interpolation matrix is the left one + a fraction of the difference:
matrix = allMatrices{idx} + fraction * (allMatrices{idx+1}-allMatrices{idx});

Note, you need to handle the cases thick<0 and thick>=35 with care.

Titus

[Yun Inn]

Hi Titus

What do I do if thick is also a 2D matrix?

[Titus Edelhofer]

Hmm, with the original question/answer you get the 2D interpolation matrix for one thickness. If thick is a 2D matrix (say NxM), and you loop, you will get N*M interpolation matrices of size 1024x1024. If N and M are not too large, this is no problem.