*/
private static double logGammaSum(final double a, final double b)
throws OutOfRangeException {
if ((a < 1.0) || (a > 2.0)) {
throw new OutOfRangeException(a, 1.0, 2.0);
}
if ((b < 1.0) || (b > 2.0)) {
throw new OutOfRangeException(b, 1.0, 2.0);
}
final double x = (a - 1.0) + (b - 1.0);
if (x <= 0.5) {
return Gamma.logGamma1p(1.0 + x);