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.. highlight:: c
.. _complexobjects:
Complex Number Objects
----------------------
.. index:: object: complex number
Python's complex number objects are implemented as two distinct types when
viewed from the C API: one is the Python object exposed to Python programs, and
the other is a C structure which represents the actual complex number value.
The API provides functions for working with both.
Complex Numbers as C Structures
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Note that the functions which accept these structures as parameters and return
them as results do so *by value* rather than dereferencing them through
pointers. This is consistent throughout the API.
.. c:type:: Py_complex
The C structure which corresponds to the value portion of a Python complex
number object. Most of the functions for dealing with complex number objects
use structures of this type as input or output values, as appropriate. It is
defined as::
typedef struct {
double real;
double imag;
} Py_complex;
.. c:function:: Py_complex _Py_c_sum(Py_complex left, Py_complex right)
Return the sum of two complex numbers, using the C :c:type:`Py_complex`
representation.
.. c:function:: Py_complex _Py_c_diff(Py_complex left, Py_complex right)
Return the difference between two complex numbers, using the C
:c:type:`Py_complex` representation.
.. c:function:: Py_complex _Py_c_neg(Py_complex num)
Return the negation of the complex number *num*, using the C
:c:type:`Py_complex` representation.
.. c:function:: Py_complex _Py_c_prod(Py_complex left, Py_complex right)
Return the product of two complex numbers, using the C :c:type:`Py_complex`
representation.
.. c:function:: Py_complex _Py_c_quot(Py_complex dividend, Py_complex divisor)
Return the quotient of two complex numbers, using the C :c:type:`Py_complex`
representation.
If *divisor* is null, this method returns zero and sets
:c:data:`errno` to :c:data:`EDOM`.
.. c:function:: Py_complex _Py_c_pow(Py_complex num, Py_complex exp)
Return the exponentiation of *num* by *exp*, using the C :c:type:`Py_complex`
representation.
If *num* is null and *exp* is not a positive real number,
this method returns zero and sets :c:data:`errno` to :c:data:`EDOM`.
Complex Numbers as Python Objects
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. c:type:: PyComplexObject
This subtype of :c:type:`PyObject` represents a Python complex number object.
.. c:var:: PyTypeObject PyComplex_Type
This instance of :c:type:`PyTypeObject` represents the Python complex number
type. It is the same object as :class:`complex` in the Python layer.
.. c:function:: int PyComplex_Check(PyObject *p)
Return true if its argument is a :c:type:`PyComplexObject` or a subtype of
:c:type:`PyComplexObject`. This function always succeeds.
.. c:function:: int PyComplex_CheckExact(PyObject *p)
Return true if its argument is a :c:type:`PyComplexObject`, but not a subtype of
:c:type:`PyComplexObject`. This function always succeeds.
.. c:function:: PyObject* PyComplex_FromCComplex(Py_complex v)
Create a new Python complex number object from a C :c:type:`Py_complex` value.
.. c:function:: PyObject* PyComplex_FromDoubles(double real, double imag)
Return a new :c:type:`PyComplexObject` object from *real* and *imag*.
.. c:function:: double PyComplex_RealAsDouble(PyObject *op)
Return the real part of *op* as a C :c:expr:`double`.
.. c:function:: double PyComplex_ImagAsDouble(PyObject *op)
Return the imaginary part of *op* as a C :c:expr:`double`.
.. c:function:: Py_complex PyComplex_AsCComplex(PyObject *op)
Return the :c:type:`Py_complex` value of the complex number *op*.
If *op* is not a Python complex number object but has a :meth:`__complex__`
method, this method will first be called to convert *op* to a Python complex
number object. If ``__complex__()`` is not defined then it falls back to
:meth:`__float__`. If ``__float__()`` is not defined then it falls back
to :meth:`__index__`. Upon failure, this method returns ``-1.0`` as a real
value.
.. versionchanged:: 3.8
Use :meth:`__index__` if available.
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