def update_coefs(self):
"""(Re)calculate the MA coefficients based on the instantaneous
unit hydrograph."""
coefs = []
sum_coefs = 0.
moment1 = self.iuh.moment1
for t in itertools.count(0., 1.):
points = (moment1 % 1, ) if t <= moment1 <= (t + 2.) else ()
try:
coef = integrate.quad(self._quad,
0.,
1.,
args=(t, ),
points=points)[0]
except integrate.IntegrationWarning:
idx = int(moment1)
coefs = numpy.zeros(idx + 2, dtype=float)
weight = (moment1 - idx)
coefs[idx] = (1. - weight)
coefs[idx + 1] = weight
self.coefs = coefs
warnings.warn(
'During the determination of the MA coefficients '
'corresponding to the instantaneous unit hydrograph '
'`%s` a numerical integration problem occurred. '
'Please check the calculated coefficients: %s.' %
(repr(self.iuh), objecttools.repr_values(coefs)))
break # pragma: no cover
sum_coefs += coef
if (sum_coefs > .9) and (coef < self.smallest_coeff):
coefs = numpy.array(coefs)
coefs /= numpy.sum(coefs)
self.coefs = coefs
break
coefs.append(coef)
def turningpoint(self):
"""Turning point (index and value tuple) in the recession part of the
MA approximation of the instantaneous unit hydrograph."""
coefs = self.coefs
old_dc = coefs[1] - coefs[0]
for idx in range(self.order - 2):
new_dc = coefs[idx + 2] - coefs[idx + 1]
if (old_dc < 0.0) and (new_dc > old_dc):
return idx, coefs[idx]
old_dc = new_dc
raise RuntimeError(
"Not able to detect a turning point in the impulse response "
"defined by the MA coefficients %s." %
objecttools.repr_values(coefs))