def integrate_start(self, t, y):
"""
Helper program for the initialization of LSODAR
"""
#print ' We have rkstarter {} and rkstarter_active {}'.format(self.rkstarter, self._rkstarter_active)
if not (self.rkstarter > 1 and self._rkstarter_active):
# first call or classical restart after a discontinuity
ISTATE = 1
# reset work arrays
RWORK = 0.0 * self._RWORK
IWORK = 0.0 * self._IWORK
else: #self.rkstarter and self._rkstarter_active
# RK restart
RWORK = self._RWORK.copy()
IWORK = self._IWORK.copy()
ISTATE = 2 # should be 2
dls001 = common_like()
dlsr01 = common_like()
# invoke rkstarter
# a) get previous stepsize if any
hu, nqu, nq, nyh, nqnyh = get_lsod_common()
#H = hu if hu != 0. else 1.e-4 # this needs some reflections
#H =(abs(RWORK[0]-t)*((self.options["rtol"])**(1/(self.rkstarter+1))))/(100*Sc.norm(self.problem.rhs(t,y,self.sw))+10)#if hu != 0. else 1.e-4
H = 1e-2
#H=self.autostart(t,y)
#H=3*H
# b) compute the Nordsieck array and put it into RWORK
rkNordsieck = RKStarterNordsieck(self.problem.rhs,
H,
number_of_steps=self.rkstarter)
t, nordsieck = rkNordsieck(t, y, self.sw)
nordsieck = nordsieck.T
nordsieck_start_index = 21 + 3 * self.problem_info["dimRoot"] - 1
RWORK[nordsieck_start_index:nordsieck_start_index+nordsieck.size] = \
nordsieck.flatten(order='F')
# c) compute method coefficients and update the common blocks
dls001.init = 1
#dls001.jstart = -1.0 #take the next step with a new value of H,n,meth,..
mf = 20
nq = self.rkstarter
dls001.meth = meth = mf // 10
dls001.miter = mf % 10
elco, tesco = dcfode(meth) #
dls001.maxord = 5 #max order
dls001.nq = self.rkstarter #Next step order
dls001.nqu = self.rkstarter #Method order last used (check if this is needed)
dls001.meo = meth #meth
dls001.nqnyh = nq * self.problem_info["dim"] #nqnyh
dls001.conit = 0.5 / (nq + 2) #conit
dls001.el = elco[:, nq - 1] # el0 is set internally
dls001.hu = H # this sets also hold and h internally
dls001.jstart = 1
# IWORK[...] =
#IWORK[13]=dls001.nqu
IWORK[14] = dls001.nq
#IWORK[18]=dls001.meth
#IWORK[7]=dlsa01.mxordn #max allowed order for Adams methods
#IWORK[8]=dlsa01.mxords #max allowed order for BDF
IWORK[19] = meth #the current method indicator
#RWORK[...]
dls001.tn = t
RWORK[12] = t
RWORK[10] = hu #step-size used successfully
RWORK[11] = H #step-size to be attempted for the next step
#RWORK[6]=dls001.hmin
#RWORK[5]=dls001.hmxi
number_of_fevals = N.array([1, 2, 4, 7, 11])
# d) Reset statistics
IWORK[9:13] = [0] * 4
dls001.nst = 1
dls001.nfe = number_of_fevals[self.rkstarter -
1] # from the starter
dls001.nje = 0
dlsr01.nge = 0
# set common block
commonblocks = {}
commonblocks.update(dls001())
commonblocks.update(dlsr01())
set_lsod_common(**commonblocks)
return ISTATE, RWORK, IWORK
def test_setcoefficients(self):
elco, tesco = dcfode(1)
nose.tools.assert_almost_equal(elco[0, 2], 5. / 12., 9) # AM-2
nose.tools.assert_almost_equal(tesco[0, 2], 2., 9) # AM-2 error coeff