divides each column by its standard deviation
[x_std,std] = standardize(x,nbr);
a matrix (n x q) or a Div structure
any numerical or string character; if present, the standardization is processed with (n-1) instead of the default value n
a Div structure obtained by dividing the columns of x by their standard deviation
the standard deviations
std.d is a vector (1 x q)