def _ttr(self, k_data, size, prob):
"""Krawtchouk rule"""
from chaospy.quadrature import discretized_stieltjes
abscissas = numpy.arange(0, numpy.floor(size)+1)
weights = self._pdf(abscissas, size, prob)
(alpha, beta), _, _ = discretized_stieltjes(k_data, [abscissas], weights)
return alpha[0, -1], beta[0, -1]
def _ttr(self, k_data, lower, upper):
"""Three terms recurrence coefficients."""
from chaospy.quadrature import discretized_stieltjes
abscissas = numpy.arange(numpy.ceil(lower), numpy.floor(upper)+1)
weights = numpy.repeat(1./len(abscissas), len(abscissas))
(alpha, beta), _, _ = discretized_stieltjes(k_data, [abscissas], weights)
return alpha[0, -1], beta[0, -1]