def derivative(self, vf):
"""Derivative of the point-wise norm operator at ``vf``.
The derivative at ``F`` of the point-wise norm operator ``N``
with finite exponent ``p`` and weights ``w`` is the pointwise
inner product with the vector field
``x --> N(F)(x)^(1-p) * [ F_j(x) * |F_j(x)|^(p-2) ]_j``.
Note that this is not well-defined for ``F = 0``. If ``p < 2``,
any zero component will result in a singularity.
Parameters
----------
vf : `domain` `element-like`
Vector field ``F`` at which to evaluate the derivative.
Returns
-------
deriv : `PointwiseInner`
Derivative operator at the given point ``vf``.
Raises
------
NotImplementedError
* if the vector field space is complex, since the derivative
is not linear in that case
* if the exponent is ``inf``
"""
if self.domain.field == ComplexNumbers():
raise NotImplementedError('operator not Frechet-differentiable '
'on a complex space')
if self.exponent == float('inf'):
raise NotImplementedError('operator not Frechet-differentiable '
'for exponent = inf')
vf = self.domain.element(vf)
vf_pwnorm_fac = self(vf)
if self.exponent != 2: # optimize away most common case.
vf_pwnorm_fac **= (self.exponent - 1)
inner_vf = vf.copy()
for gi in inner_vf:
# This is the old line from odl version 0.6.0.
#gi /= vf_pwnorm_fac * gi ** (self.exponent - 2)
tmp = vf_pwnorm_fac * gi**(self.exponent - 2)
gi = np.divide(gi, tmp, where=tmp != 0)
return PointwiseInner(self.domain, inner_vf, weighting=self.weights)
def _call(self, vf, out):
"""Implement ``self(vf, out)``."""
if self.domain.field == ComplexNumbers():
vf[0].multiply(self._vecfield[0].conj(), out=out)
else:
vf[0].multiply(self._vecfield[0], out=out)
if self.is_weighted:
out *= self.weights[0]
if self.domain.size == 1:
return
tmp = self.range.element()
for vfi, gi, wi in zip(vf[1:], self.vecfield[1:], self.weights[1:]):
if self.domain.field == ComplexNumbers():
vfi.multiply(gi.conj(), out=tmp)
else:
vfi.multiply(gi, out=tmp)
if self.is_weighted:
tmp *= wi
out += tmp
def __init__(self, size, dtype):
"""Initialize a new instance.
Parameters
----------
size : non-negative int
Number of entries in a tuple.
dtype :
Data type for each tuple entry. Can be provided in any
way the `numpy.dtype` function understands, most notably
as built-in type, as one of NumPy's internal datatype
objects or as string.
Only scalar data types (numbers) are allowed.
"""
NtuplesBase.__init__(self, size, dtype)
if not is_scalar_dtype(self.dtype):
raise TypeError('{!r} is not a scalar data type'.format(dtype))
if is_real_dtype(self.dtype):
field = RealNumbers()
self.__is_real = True
self.__real_dtype = self.dtype
self.__real_space = self
try:
self.__complex_dtype = complex_dtype(self.dtype)
except ValueError:
self.__complex_dtype = None
self.__complex_space = None # Set in first call of astype
else:
field = ComplexNumbers()
self.__is_real = False
try:
self.__real_dtype = real_dtype(self.dtype)
except ValueError:
self.__real_dtype = None
self.__real_space = None # Set in first call of astype
self.__complex_dtype = self.dtype
self.__complex_space = self
self.__is_floating = is_floating_dtype(self.dtype)
LinearSpace.__init__(self, field)
def cn(size, dtype=None, impl='numpy', **kwargs):
"""Return the complex vector space ``C^n``.
Parameters
----------
size : positive int
The number of dimensions of the space
dtype : `object`, optional
The data type of the storage array. Can be provided in any
way the `numpy.dtype` function understands, most notably
as built-in type, as one of NumPy's internal datatype
objects or as string.
Only complex floating-point data types are allowed.
Default: default of the implementation given by calling
``default_dtype(ComplexNumbers())`` on the `FnBase` implementation.
impl : string, optional
The backend to use. See `odl.space.entry_points.FN_IMPLS` for
available options.
kwargs :
Extra keyword arguments to pass to the implmentation.
Returns
-------
cn : `FnBase`
See Also
--------
fn : n-tuples over a field with arbitrary scalar data type.
"""
cn_impl = FN_IMPLS[impl]
if dtype is None:
dtype = cn_impl.default_dtype(ComplexNumbers())
cn = cn_impl(size, dtype, **kwargs)
if not cn.is_cn:
raise TypeError('data type {!r} not a complex floating-point type.'
''.format(dtype))
return cn
def __str__(self):
"""Return ``str(self)``."""
inner_str = '{}'.format(self.domain)
dtype_str = dtype_repr(self.out_dtype)
if self.field == RealNumbers():
if self.out_dtype == np.dtype('float64'):
pass
else:
inner_str += ', out_dtype={}'.format(dtype_str)
elif self.field == ComplexNumbers():
if self.out_dtype == np.dtype('complex128'):
inner_str += ', field={!r}'.format(self.field)
else:
inner_str += ', out_dtype={}'.format(dtype_str)
else: # different field, name explicitly
inner_str += ', field={!r}'.format(self.field)
inner_str += ', out_dtype={}'.format(dtype_str)
return '{}({})'.format(self.__class__.__name__, inner_str)
def __init__(self, domain, field=None, out_dtype=None):
"""Initialize a new instance.
Parameters
----------
domain : `Set`
The domain of the functions
field : `Field`, optional
The range of the functions, usually the `RealNumbers` or
`ComplexNumbers`. If not given, the field is either inferred
from ``out_dtype``, or, if the latter is also ``None``, set
to ``RealNumbers()``.
out_dtype : optional
Data type of the return value of a function in this space.
Can be given in any way `numpy.dtype` understands, e.g. as
string (``'float64'``) or data type (``float``).
By default, ``'float64'`` is used for real and ``'complex128'``
for complex spaces.
"""
if not isinstance(domain, Set):
raise TypeError('`domain` {!r} not a Set instance'.format(domain))
if field is not None and not isinstance(field, Field):
raise TypeError('`field` {!r} not a `Field` instance'
''.format(field))
# Data type: check if consistent with field, take default for None
dtype, dtype_in = np.dtype(out_dtype), out_dtype
# Default for both None
if field is None and out_dtype is None:
field = RealNumbers()
out_dtype = np.dtype('float64')
# field None, dtype given -> infer field
elif field is None:
if is_real_dtype(dtype):
field = RealNumbers()
elif is_complex_floating_dtype(dtype):
field = ComplexNumbers()
else:
raise ValueError('{} is not a scalar data type'
''.format(dtype_in))
# field given -> infer dtype if not given, else check consistency
elif field == RealNumbers():
if out_dtype is None:
out_dtype = np.dtype('float64')
elif not is_real_dtype(dtype):
raise ValueError('{} is not a real data type'
''.format(dtype_in))
elif field == ComplexNumbers():
if out_dtype is None:
out_dtype = np.dtype('complex128')
elif not is_complex_floating_dtype(dtype):
raise ValueError('{} is not a complex data type'
''.format(dtype_in))
# Else: keep out_dtype=None, which results in lazy dtype determination
LinearSpace.__init__(self, field)
FunctionSet.__init__(self, domain, field, out_dtype)
# Init cache attributes for real / complex variants
if self.field == RealNumbers():
self.__real_out_dtype = self.out_dtype
self.__real_space = self
self.__complex_out_dtype = complex_dtype(self.out_dtype,
default=np.dtype(object))
self.__complex_space = None
elif self.field == ComplexNumbers():
self.__real_out_dtype = real_dtype(self.out_dtype)
self.__real_space = None
self.__complex_out_dtype = self.out_dtype
self.__complex_space = self
else:
self.__real_out_dtype = None
self.__real_space = None
self.__complex_out_dtype = None
self.__complex_space = None
def __init__(self, adjoint, vfspace, vecfield, weighting=None):
"""Initialize a new instance.
All parameters are given according to the specifics of the "usual"
operator. The ``adjoint`` parameter is used to control conversions
for the inverse transform.
Parameters
----------
adjoint : bool
``True`` if the operator should be the adjoint, ``False``
otherwise.
vfspace : `ProductSpace`
Space of vector fields on which the operator acts.
It has to be a product space of identical spaces, i.e. a
power space.
vecfield : ``vfspace`` `element-like`
Vector field with which to calculate the point-wise inner
product of an input vector field
weighting : `array-like` or float, optional
Weighting array or constant for the norm. If an array is
given, its length must be equal to ``domain.size``.
By default, the weights are is taken from
``domain.weighting``. Note that this excludes unusual
weightings with custom inner product, norm or dist.
"""
if not isinstance(vfspace, ProductSpace):
raise TypeError('`vfsoace` {!r} is not a ProductSpace '
'instance'.format(vfspace))
if adjoint:
super().__init__(domain=vfspace[0],
range=vfspace,
base_space=vfspace[0],
linear=True)
else:
super().__init__(domain=vfspace,
range=vfspace[0],
base_space=vfspace[0],
linear=True)
# Bail out if the space is complex but we cannot take the complex
# conjugate.
if (vfspace.field == ComplexNumbers()
and not hasattr(self.base_space.element_type, 'conj')):
raise NotImplementedError(
'base space element type {!r} does not implement conj() '
'method required for complex inner products'
''.format(self.base_space.element_type))
self._vecfield = vfspace.element(vecfield)
# Handle weighting, including sanity checks
if weighting is None:
if hasattr(vfspace.weighting, 'array'):
self.__weights = vfspace.weighting.array
elif hasattr(vfspace.weighting, 'const'):
self.__weights = (vfspace.weighting.const *
np.ones(len(vfspace)))
else:
raise ValueError('weighting scheme {!r} of the domain does '
'not define a weighting array or constant'
''.format(vfspace.weighting))
elif np.isscalar(weighting):
self.__weights = float(weighting) * np.ones(vfspace.size)
else:
self.__weights = np.asarray(weighting, dtype='float64')
self.__is_weighted = not np.array_equiv(self.weights, 1.0)
def cn(shape, dtype=None, impl='numpy', **kwargs):
"""Return a space of complex tensors.
Parameters
----------
shape : positive int or sequence of positive ints
Number of entries per axis for elements in this space. A
single integer results in a space with 1 axis.
dtype : optional
Data type of each element. Can be provided in any way the
`numpy.dtype` function understands, e.g. as built-in type or
as a string. Only complex floating-point data types are allowed.
For ``None``, the `TensorSpace.default_dtype` of the
created space is used in the form
``default_dtype(ComplexNumbers())``.
impl : str, optional
Impmlementation back-end for the space. See
`odl.space.entry_points.tensor_space_impl_names` for available
options.
kwargs :
Extra keyword arguments passed to the space constructor.
Returns
-------
cn : `TensorSpace`
Examples
--------
Space of complex 3-tuples with ``complex64`` entries:
>>> odl.cn(3, dtype='complex64')
cn(3, dtype='complex64')
Complex 2x3 tensors with ``complex64`` entries:
>>> odl.cn((2, 3), dtype='complex64')
cn((2, 3), dtype='complex64')
The default data type depends on the implementation. For
``impl='numpy'``, it is ``'complex128'``:
>>> space = odl.cn((2, 3))
>>> space
cn((2, 3))
>>> space.dtype
dtype('complex128')
See Also
--------
tensor_space : Space of tensors with arbitrary scalar data type.
rn : Real tensor space.
"""
cn_cls = tensor_space_impl(impl)
if dtype is None:
dtype = cn_cls.default_dtype(ComplexNumbers())
# Use args by keyword since the constructor may take other arguments
# by position
cn = cn_cls(shape=shape, dtype=dtype, **kwargs)
if not cn.is_complex:
raise ValueError('data type {!r} not a complex floating-point type.'
''.format(dtype))
return cn
