Pitman-Yor Sequence Measure.
Sq_pitmanyor(d, alpha = 1, m = 1L)A seq_measure object for use in the exchangeable sequence
resampling scheme for mixtures.
The discount parameter for the Pitman-Yor process. Must be less than 1.
The concentration parameter for the Pitman-Yor process. Must be
greater than -sigma if sigma is in [0, 1), else ignored.
A positive integer used to set theta = m * abs(sigma) if sigma
is negative.
seq_measure(), seqre()