Mesma n_models question

[nealresearch]

Hello,

I am trying to understand how does the n_model parameter work. In my understanding the n_models is the number of combination for the endmembers. For example if i have four classes and i pick two pure pixel then, the class column will look like this "c("grass", "urban", "trees", "soil", "grass", "urban", "trees", "soil")" and as there are two set of endmember for each class there will two model of the first four class and the second four class. But if we have two set of endmembers for each class then shouldnt the model number be 16, as we can create 16 combination. It automatically set the n_models to 2, when i pass my vector as class column.

Or another theory i have is that it only combines two set of endmember for example model1 : grass + urban
model2: trees + soil if we say n_model = 2 and if pass one more set of the endmembers for all the four class, the number of model increases to three and then combines model1: grass + urban + trees...

I would appreciate if someone can clarify how the parameter works.