Linear fit for data from 3D matrix

Hello community! I have a 3D matrix like this:

val(:,:,1) =
      2.5620    2.0040    1.8380
      2.2240    1.9160    1.9030
val(:,:,2) =
      2.0330    1.9970    1.8180
      2.4040    1.9330    1.9300
val(:,:,3) =
      2.4260    2.1040    1.9050
      1.9960    1.9630    1.9560

I need to make a linear fit for every group on z axis (here for example, 2.5620, 2.0330, 2.4260). For the fit in 2D plot (just to make it clear, I do not need the plot), the y axis is the same as the z axis of the 3D matrix (suppose simply 1,2 and 3)and x axis is based on the values of the element. After this, I have to get the values on the fit (by y=1,2 and 3) and use the values in 3D matrix minus the values from the fit. Could someone please help me on this? Thank you very much!

[Star Strider]

I’m not entirely clear on what you’re asking. Please give an example of what you want to fit, specifying your independent and dependent variables.