Mathematically, a complex number is a number of the form
i is the imaginary number, equal to the
square root of -1.
Complex numbers are quite commonly used in electrical
engineering. In that field, however, because the symbol
i is used to represent current, they use
j for the square root of -1.
Python adheres to this convention: a number followed by
j” is treated as an imaginary
number. Python displays complex numbers in parentheses when
they have a nonzero real part.
>>> 5j 5j >>> 1+2.56j (1+2.5600000000000001j) >>> (1+2.56j)*(-1-3.44j) (7.8064-6j)
Unlike Python's other numeric types, complex numbers are
a composite quantity made of two parts: the real part and
the imaginary part, both of which are represented
float values. You can
retrieve the two components using attribute references.
For a complex number
the real part.
the imaginary part as a
float, not as
>>> a=(1+2.56j)*(-1-3.44j) >>> a (7.8064-6j) >>> a.real 7.8064 >>> a.imag -6.0
To construct a
complex value from two
float values, see Section 20.9, “
complex(): Convert to