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Reputation: 4996

real and imaginary part of a complex number in polar form

I am a bit confused about the proper way to deal with complex numbers in polar form and the way to separate its real and imaginary part.

Notice that I am expecting as real part the radius, as imaginary part the angle.

The inbuilt re and im functions get always the real and imaginary part of the Cartesian representation of the complex number.

Here an example

from sympy import I, pi, re, im, exp, sqrt

# complex num in Cartesian form
z = -4 + I*4
print(re(z), im(z))
# 4 -4

# complex num in polar form
z = 4* sqrt(2) * exp(I * pi * 3/4)
print(re(z), im(z))
# 4 -4  but expacting 4*sqrt(2), pi*3/4

What is the most SymPytonic way to deal with such problem?

Upvotes: 3

Views: 176

Answers (2)

orlp
orlp

Reputation: 117771

Complex numbers aren't "in polar form", or "in Cartesian representation", they just are. You can convert them into a polar form, or to a Cartesian representation.

re and im convert to such a Cartesian representation. If you want to convert to a polar form you'll need to actually do that. In Sympy the pair of functions for that is sp.Abs to get the magnitude of the complex number, and sp.arg to get the complex argument.

Upvotes: 4

Davide_sd
Davide_sd

Reputation: 13185

Maybe you are looking for Abs and arg functions?

z = -4 + I*4
print(Abs(z), arg(z))
# 4*sqrt(2) 3*pi/4

z = 4* sqrt(2) * exp(I * pi * 3/4)
print(Abs(z), arg(z))
# 4*sqrt(2) 3*pi/4

Upvotes: 3

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