  We propose two algorithms for sampling from two gamma variates possessing a
negative correlation. The case of positive correlation is easily solved, so we
just mention it. The main problem is the lowest value of the correlation
coefficient that can be reached. The starting point of both algorithms is
generation from a bivariate density with uniform negatively correlated
marginals. Actually the first method uses a degenerate bivariate density since
it considers two uniforms related by a linear relationship. Then we resort
essentially to the inverse transform method. For both algorithms we stress
restrictions on the parameters and rigidities.
