def _fifi2fid(x):
x = kept_within(0.0, x)
cdf = cerlang_gen(nshapes, qumul, phasemean, x)
pdf = derlang_gen(nshapes, qumul, phasemean, x)
fi = cdf - prob
if pdf <= 0.0:
if fi == 0.0: fi2fid = 1.0
else: fi2fid = MAXFLOAT
else:
fi2fid = fi/pdf
return fi, fi2fid
def rerlang_gen(self, nshapes, qumul, phasemean, \
xmax=float('inf'), pmax=1.0):
"""
The generalized Erlang distribution - the Erlang equivalent of the
rhyperexpo generator
f = sumk pk * ferlang(m, nk), F = sumk pk * Ferlang(m, nk), the same
mean for all phases.
NB Input to the function is the list of CUMULATIVE FREQUENCIES !
"""
assert xmax >= 0.0, "xmax must be a non-negative float in rerlang_gen!"
self._checkpmax(pmax, 'rerlang_gen')
pmx = pmax
if xmax < float('inf'): \
pmx = min(pmax, cerlang_gen(nshapes, qumul, phasemean, xmax))
p = pmx * self.runif01()
x = ierlang_gen(p, nshapes, qumul, phasemean)
return x