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# Logarithm of the sum of exponentiations of the inputs in base-2 in Numpy

To get the Logarithm of the sum of exponentiations of the inputs in base 2, use the **numpy.logaddexp()** method in Python Numpy.

Calculates **log2(2**x1 + 2**x2)**. This function is useful in machine learning when the calculated probabilities of events may be so small as to exceed the range of normal floating-point numbers. In
such cases the base-2 logarithm of the calculated probability can be used instead. This function allows adding probabilities stored in such a fashion.

NumPy offers comprehensive mathematical functions, random number generators, linear algebra routines, Fourier transforms, and more. It supports a wide range of hardware and computing platforms, and plays well with distributed, GPU, and sparse array libraries.

## Steps

At first, import the required library −

import numpy as np

Log2 input −

one = np.log2(2e-50) two = np.log2(3.2e-50)

Display the log input −

print("Value 1...

", one) print("Value 2...

", two)

To get the Logarithm of the sum of exponentiations of the inputs in base 2, use the numpy.logaddexp() method −

res = np.logaddexp(one, two) print("

Logarithm of the sum of exponentiations of the inputs in base 2...

",res)

## Example

import numpy as np # Calculates log2(2**x1 + 2**x2). # This function is useful in machine learning when the calculated probabilities of events may be so small # as to exceed the range of normal floating point numbers. # In such cases the base-2 logarithm of the calculated probability can be used instead. # This function allows adding probabilities stored in such a fashion. # Log2 input one = np.log2(2e-50) two = np.log2(3.2e-50) # Display the log input print("Value 1...

", one) print("Value 2...

", two) # To get the Logarithm of the sum of exponentiations of the inputs in base 2, use the numpy.logaddexp() method in Python Numpy res = np.logaddexp(one, two) print("

Logarithm of the sum of exponentiations of the inputs in base 2...

",res)

## Output

Value 1... -165.09640474436813 Value 2... -164.41833283925547 Logarithm of the sum of exponentiations of the inputs in base 2... -164.00781734564688

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