function mc = slowmedcouple(z)
  n = length(z);
  n2 = ceil(n/2);
  z = sort(z, "descend");
  zmed = median(z);
  z -= zmed;
  zplus = z(z >= 0);
  zminus = z(z <= 0)';
  zz = (zplus + zminus)./(zplus - zminus);
  zz(isnan(zz)) = 0;
  zzsort = sort(zz(:), "descend");
  medc_idx = ceil(n2^2/2);
  mc = zzsort(medc_idx);
  printf("%.16g\n", mc);
endfunction