def __init__(self, pct_drift=None, pct_vol=None, time_unit=dt.timedelta(days=1)):
if pct_drift is None and pct_vol is None:
pct_drift = 0.; pct_vol = 1.
self._pct_drift, self._pct_vol = None, None
if pct_drift is not None:
self._pct_drift = npu.to_ndim_2(pct_drift, ndim_1_to_col=True, copy=True)
process_dim = npu.nrow(self._pct_drift)
if pct_vol is not None:
self._pct_vol = npu.to_ndim_2(pct_vol, ndim_1_to_col=True, copy=True)
process_dim = npu.nrow(self._pct_vol)
if self._pct_drift is None: self._pct_drift = npu.col_of(process_dim, 0.)
if self._pct_vol is None: self._pct_vol = np.eye(process_dim)
npc.check_col(self._pct_drift)
npc.check_nrow(self._pct_drift, process_dim)
npc.check_nrow(self._pct_vol, process_dim)
noise_dim = npu.ncol(self._pct_vol)
self._pct_cov = stats.vol_to_cov(self._pct_vol)
npu.make_immutable(self._pct_drift)
npu.make_immutable(self._pct_vol)
npu.make_immutable(self._pct_cov)
self._to_string_helper_GeometricBrownianMotion = None
self._str_GeometricBrownianMotion = None
super(GeometricBrownianMotion, self).__init__(process_dim=process_dim, noise_dim=noise_dim,
drift=lambda t, x: self._pct_drift * x,
diffusion=lambda t, x: x * self._pct_vol,
time_unit=time_unit)
def __init__(self, mean=None, vol=None, time_unit=dt.timedelta(days=1)):
if mean is None and vol is None:
mean = 0.; vol = 1.
self._mean, self._vol = None, None
if mean is not None:
self._mean = npu.to_ndim_2(mean, ndim_1_to_col=True, copy=True)
process_dim = npu.nrow(self._mean)
if vol is not None:
self._vol = npu.to_ndim_2(vol, ndim_1_to_col=True, copy=True)
process_dim = npu.nrow(self._vol)
if self._mean is None: self._mean = npu.col_of(process_dim, 0.)
if self._vol is None: self._vol = np.eye(process_dim)
npc.check_col(self._mean)
npc.check_nrow(self._mean, process_dim)
npc.check_nrow(self._vol, process_dim)
noise_dim = npu.ncol(self._vol)
self._cov = stats.vol_to_cov(self._vol)
npu.make_immutable(self._mean)
npu.make_immutable(self._vol)
npu.make_immutable(self._cov)
self._to_string_helper_WienerProcess = None
self._str_WienerProcess = None
super(WienerProcess, self).__init__(process_dim=process_dim, noise_dim=noise_dim,
drift=lambda t, x: self._mean, diffusion=lambda t, x: self._vol,
time_unit=time_unit)
def __init__(self,
initial_value=None,
final_value=None,
initial_time=0.,
final_time=1.,
vol=None,
time_unit=dt.timedelta(days=1)):
process_dim = 1
self.__initial_value = None
self.__final_value = None
if initial_value is not None:
self.__initial_value = npu.to_ndim_2(initial_value,
ndim_1_to_col=True,
copy=True)
process_dim = npu.nrow(self.__initial_value)
if final_value is not None:
self.__final_value = npu.to_ndim_2(final_value,
ndim_1_to_col=True,
copy=True)
process_dim = npu.nrow(self.__final_value)
if self.__initial_value is None:
self.__initial_value = npu.col_of(process_dim, 0.)
if self.__final_value is None:
self.__final_value = npu.col_of(process_dim, 0.)
self.__vol = None
if vol is not None:
self.__vol = npu.to_ndim_2(vol, ndim_1_to_col=True, copy=True)
process_dim = npu.nrow(self.__vol)
if self.__vol is None: self.__vol = np.eye(process_dim)
self.__initial_time = initial_time
self.__final_time = final_time
npc.check_col(self.__initial_value)
npc.check_col(self.__final_value)
npc.check_nrow(self.__initial_value, process_dim)
npc.check_nrow(self.__final_value, process_dim)
noise_dim = npu.ncol(self.__vol)
self.__cov = stats.vol_to_cov(self.__vol)
npu.make_immutable(self.__initial_value)
npu.make_immutable(self.__final_value)
npu.make_immutable(self.__vol)
npu.make_immutable(self.__cov)
self._to_string_helper_BrownianBridge = None
self._str_BrownianBridge = None
super(BrownianBridge,
self).__init__(process_dim=process_dim,
noise_dim=noise_dim,
drift=lambda t, x: (self.__final_value - x) /
(self.__final_time - t),
diffusion=lambda t, x: self.__vol,
time_unit=time_unit)
def __init__(self, transition=None, mean=None, vol=None, time_unit=dt.timedelta(days=1)):
if transition is None and mean is None and vol is None:
transition = 1.; mean = 0.; vol = 1.
self._transition, self._mean, self._vol = None, None, None
if transition is not None:
self._transition = npu.to_ndim_2(transition, ndim_1_to_col=True, copy=True)
process_dim = npu.nrow(self._transition)
if mean is not None:
self._mean = npu.to_ndim_2(mean, ndim_1_to_col=True, copy=True)
process_dim = npu.nrow(self._mean)
if vol is not None:
self._vol = npu.to_ndim_2(vol, ndim_1_to_col=True, copy=True)
process_dim = npu.nrow(self._vol)
if self._transition is None: self._transition = np.eye(process_dim)
if self._mean is None: self._mean = npu.col_of(process_dim, 0.)
if self._vol is None: self._vol = np.eye(process_dim)
npc.check_square(self._transition)
npc.check_nrow(self._transition, process_dim)
npc.check_col(self._mean)
npc.check_nrow(self._mean, process_dim)
npc.check_nrow(self._vol, process_dim)
noise_dim = npu.ncol(self._vol)
self._transition_x_2 = npu.kron_sum(self._transition, self._transition)
self._transition_x_2_inverse = np.linalg.inv(self._transition_x_2)
self._cov = stats.vol_to_cov(self._vol)
self._cov_vec = npu.vec(self._cov)
self._cached_mean_reversion_factor = None
self._cached_mean_reversion_factor_time_delta = None
self._cached_mean_reversion_factor_squared = None
self._cached_mean_reversion_factor_squared_time_delta = None
npu.make_immutable(self._transition)
npu.make_immutable(self._transition_x_2)
npu.make_immutable(self._transition_x_2_inverse)
npu.make_immutable(self._mean)
npu.make_immutable(self._vol)
npu.make_immutable(self._cov)
npu.make_immutable(self._cov_vec)
self._to_string_helper_OrnsteinUhlenbeckProcess = None
self._str_OrnsteinUhlenbeckProcess = None
super(OrnsteinUhlenbeckProcess, self).__init__(process_dim=process_dim, noise_dim=noise_dim,
drift=lambda t, x: -np.dot(self._transition, x - self._mean),
diffusion=lambda t, x: self._vol,
time_unit=time_unit)
def __init__(self, mean_of_log=None, cov_of_log=None, vol_of_log=None, dim=None, copy=True):
if mean_of_log is not None and dim is not None and np.size(mean_of_log) == 1:
mean_of_log = npu.col_of(dim, npu.to_scalar(mean_of_log))
if mean_of_log is None and vol_of_log is None and cov_of_log is None:
self._dim = 1 if dim is None else dim
mean_of_log = npu.col_of(self._dim, 0.)
cov_of_log = np.eye(self._dim)
vol_of_log = np.eye(self._dim)
self._dim, self._mean_of_log, self._vol_of_log, self._cov_of_log = None, None, None, None
# TODO We don't currently check whether cov_of_log and vol_of_log are consistent, i.e. that cov_of_log = np.dot(vol_of_log, vol_of_log.T) -- should we?
if mean_of_log is not None:
self._mean_of_log = npu.to_ndim_2(mean_of_log, ndim_1_to_col=True, copy=copy)
self._dim = npu.nrow(self._mean_of_log)
if cov_of_log is not None:
self._cov_of_log = npu.to_ndim_2(cov_of_log, ndim_1_to_col=True, copy=copy)
self._dim = npu.nrow(self._cov_of_log)
if vol_of_log is not None:
self._vol_of_log = npu.to_ndim_2(vol_of_log, ndim_1_to_col=True, copy=copy)
self._dim = npu.nrow(self._vol_of_log)
if self._mean_of_log is None: self._mean_of_log = npu.col_of(self._dim, 0.)
if self._cov_of_log is None and self._vol_of_log is None:
self._cov_of_log = np.eye(self._dim)
self._vol_of_log = np.eye(self._dim)
npc.check_col(self._mean_of_log)
npc.check_nrow(self._mean_of_log, self._dim)
if self._cov_of_log is not None:
npc.check_nrow(self._cov_of_log, self._dim)
npc.check_square(self._cov_of_log)
if self._vol_of_log is not None:
npc.check_nrow(self._vol_of_log, self._dim)
if self._cov_of_log is None: self._cov_of_log = stats.vol_to_cov(self._vol_of_log)
if self._vol_of_log is None: self._vol_of_log = stats.cov_to_vol(self._cov_of_log)
npu.make_immutable(self._mean_of_log)
npu.make_immutable(self._cov_of_log)
npu.make_immutable(self._vol_of_log)
mean = np.exp(self._mean_of_log + .5 * npu.col(*[self._cov_of_log[i,i] for i in range(self._dim)]))
cov = np.array([[np.exp(self._mean_of_log[i,0] + self._mean_of_log[j,0] + .5 * (self._cov_of_log[i,i] + self._cov_of_log[j,j])) * (np.exp(self._cov_of_log[i,j]) - 1.) for j in range(self._dim)] for i in range(self._dim)])
vol = stats.cov_to_vol(cov)
self._to_string_helper_LogNormalDistr = None
self._str_LogNormalDistr = None
super().__init__(mean, cov, vol, self._dim, copy)
def cov(self):
if self._cov is None:
self._cov = stats.vol_to_cov(self._vol)
return self._cov
