nfreq — frequence of the values in a vector or matrix
m=nfreq(x)
    Frequence of the  values in a real or  complex vector or a
    real or complex matrix x.
    For a real  or complex vector or a  real or complex matrix
    x,  m=freq(x) returns in  the first  column of
    the  size(x,'*')x2  matrix  m  the  values  of
    x  and  in the  second  column  of  this matrix  the
    frequences of the corresponding values.
Note that the  tabul function is more efficient, applies
also to vector of strings and returns a sorted m.