***** test
 x1 = burrrnd (1, 2, 1, 100, 1);
 x2 = burrrnd (1, 0.5, 2, 100, 1);
 pd = fitdist ([x1; x2], "burr", "By", [ones(100,1); 2*ones(100,1)]);
 [phat, pci] = burrfit (x1);
 assert ([pd(1).alpha, pd(1).c, pd(1).k], phat);
 assert (paramci (pd(1)), pci);
 [phat, pci] = burrfit (x2);
 assert ([pd(2).alpha, pd(2).c, pd(2).k], phat);
 assert (paramci (pd(2)), pci);
warning: burrfit: maximum number of iterations are exceeded.
warning: called from
    burrfit at line 209 column 9
    fit at line 641 column 19
    fitdist at line 261 column 17
    __test__ at line 5 column 5
    test at line 682 column 11
    /tmp/tmp.yJFEjz59YR at line 910 column 31

!!!!! test failed
burrfit: Weibull distribution fits better in X.