how to set histogram xbins in gplotmatrix() ?

Hello,

I have a data set with 3 different variables with 20 values each. (20x3)

Can I specify the number of groupings with 'hist' (xbins)? Matlab only creates 4 different groupings and I would like to have 10 groupings. The photo in the appendix shows my problem, the division into 4 groups is simply too imprecise.

Another question, I have a solution with the command:

gplotmatrix(data,[],[],[],[],[],'off','hist')

I don't understand what [ ] is doing in the function. data is 20x3 double.

Many thanks and greetings