Extract the argument (angle) of a complex value in radians.
What It Does and Why It Matters
phase(complex_value) returns the angle in the interval (-pi, pi], respecting the sign of zero in edge cases.
Step-by-Step Example
Start with the complete example below. Read the inputs and predict what the final print statement will show before you run it.
import cmath
print(cmath.phase(1j))How the Code Works
- The imports make these standard-library tools available: cmath.
- The print calls display the results. Compare these results with the method’s documented return type and the input used.
Expected output:
1.5707963267948966For the demonstrated inputs, Python displays '1.5707963267948966'. This result follows from the operation described above; change one input at a time to understand which rule matters.
What to Notice
Pay attention to the accepted input types, the returned value and the boundary behavior. Predict what changes if you replace the example input with an empty, zero, negative or missing value, where that value is meaningful for this operation.
If the task uses a library function, inspect its documented exceptions and return type before reusing it inside a larger function.
Where You Would Use This
Use this in calculations, data summaries, simulations or validation when the numerical assumptions match the task. Check input domains, units and precision before interpreting a result. A single example output does not prove a statistical conclusion.
Practice Exercise
Find the angle of 1-1j and convert it to degrees.
Before running your edited example, write down the result you expect. Then test at least one valid boundary or deliberately invalid value, using appropriate exception handling where necessary.
Reference: official Python documentation for the complete API contract and version notes.
Common Beginner Mistakes
- Assuming the phase is returned in degrees instead of radians.
- Using a numeric result without checking empty data, invalid ranges, precision and the meaning of its units.
Key Takeaways
- Extract the argument (angle) of a complex value in radians.
- phase(complex_value) returns the angle in the interval (-pi, pi], respecting the sign of zero in edge cases.
- Find the angle of 1-1j and convert it to degrees.