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pythoncomplex-numbers

Getting the phase of a complex number

I am using the following code - but not getting the phase back in the original form (3.366):

import math
import numpy as np
import cmath

Magn = 0.786236
Phase = 3.366   
cohs = Magn * math.cos(Phase) +  1j*Magn*math.sin(Phase)

Magn_value = np.absolute(cohs)
Phase_value = np.angle(cohs)

print(alpha_value)
print(phase_value)

The Magnitude is returned correctly, the phase is, however, returned as -2.9.. Why is that, and how can the original phase value be retrieved?

Solution

  • Look at the documentation for the angle method: you get the phase expressed in a given range, -π to +π. If you want it in the more positive range 0 to 2π, simply add 2π to any negative value.