I am looking for Vanzyl three components decomposition code for Matlab.
I should not use SNAP or other software because I am applying decompositions on forest stands. So I need the code to run in Matlab. If anyone has this code, please help
Thanks

Thank you for the SNAP codes, I am not sure can I use these codes in Matlab or not (I will comment it).
Using SNAP, the decompositions will be applied to each image pixel. In other words, the results are at pixel level. When we are extracting the values for forest stands (stand-level processing) so we can not use SNAP.

SNAP is mainly based on java so the code is not directly transferable. But maybe it helps you to implement it in matlab language.

Is it an option to calculate the decomposition at the pixek level and then use spatial statistics or create object features on the forest stands (e.g. as polygons)?

We talking about two options for calculating PolSAR features on stand level. The first one is calculating pixel-wise features (linear or nonlinear) followed by averaging. The second alternative is intensity averaging followed by PolSAR feature calculation. These options can be equivalent only if all operations in PolSAR feature calculation are linear. However, this is not the case. Thus, the “first” option is inadequate.