# Numpy – Get the Complex Conjugate

In this tutorial, we will look at how to get the complex conjugate of a complex number in a Numpy array. The complex conjugate of a complex number is obtained by changing the sign of the imaginary part. For example for the complex number a + bj, the complex conjugate would be a - bj.

## How to get the complex conjugate of complex values in a Numpy array?

You can use the numpy.conj() function to get (element-wise) the complex conjugate of complex numbers in a Numpy array. The following is the syntax –

# get the complex conjugate - pass scaler value or numpy array
np.conj(a)

Note that the numpy.conj() function is an alias for the numpy.conjugate() function (they both return the element-wise complex conjugate of a Numpy array).

If you pass a scalar value, it returns the complex conjugate of that value. And, if you pass a Numpy array, it returns the element-wise array of the complex conjugates.

## Examples

Let’s now look at some examples of using the above function on a scalar value and a Numpy array.

### Example 1 – Get the complex conjugate for a scalar value using numpy.conj()

First, let’s pass scaler values to the numpy.conj() function.

Let’s apply the numpy.conj() function on three scalar values – a real number, a complex number with a non-zero real part, and a complex number with the real part as 0.

import numpy as np

# get the complex conjugate
print(np.conj(14))
print(np.conj(2 + 4j))
print(np.conj(3j))

Output:

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14
(2-4j)
-3j

We get the complex conjugate for all the scalar values irrespective of whether we passed a real or a complex number as an argument.

### Example 2 – Element-wise get the complex conjugate in a Numpy array using numpy.conj()

If you apply the numpy.conj() function on an array, it will return a Numpy array of the complex conjugates for the elements inside the array.

Let’s create a 1-D array and apply the numpy.conj() function to it.

# create a numpy array
ar = np.array([1, 2+3j, 2+0j, 0+4j, 5.7, np.nan, np.inf, 1j, 0+0j])
# element-wise get the complex conjugate in ar
np.conj(ar)

Output:

array([1. -0.j, 2. -3.j, 2. -0.j, 0. -4.j, 5.7-0.j, nan-0.j, inf-0.j,
0. -1.j, 0. -0.j])

We get a Numpy array containing the complex conjugate of each value in the array ar.

## Summary

In this tutorial, we looked at how we can use the numpy.conj() function to get the complex conjugate of a complex number in a Numpy array. Keep in mind that if you apply this function on a scalar value, it returns the resulting complex conjugate whereas if you apply it on an array, it returns the array of complex conjugates.

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