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  2. Python | Tensorflow log1p () method

Python | Tensorflow log1p () method

The tensorflow.math module provides support for many basic mathematical operations. The tf.log1p () [alias tf.math.log1p ] provides support for the natural logarithmic function in Tensorflow. Expected to be input as complex numbers in the form or floating point numbers. Input type — tensor, and if the input contains more than one element, the element-wise logarithm is calculated, ,

Syntax : tf.log1p (x, name = None) or tf.math.log1p (x, name = None)

Parameters :
x : A Tensor of type bfloat16, half, float32, float64, complex64 or complex128.
name (optional): The name for the operation.

Return type : A Tensor with the same size and type as that of x.

Code # 1:

# Import Tensorflow library

import tensorflow as tf

 
# Constant vector of size 5

a = tf .constant ([ - 1.5 , - 1 , - 0.5 , 0 , 0.5 , 1 , 1.5 ], dtype = tf.float32)

  
# Using the log1p function and
# save the result to & # 39; b & # 39;

b = tf.log1p (a, name = `log1p` )

 
# Initiating a Tensorflow session
with tf .Session () as sess:

print ( ` Input type: ` , a)

print ( `Input:` , sess.run (a))

print ( `Return type:` , b)

print ( ` Output: ` , sess.run (b))

Output: 

 Input type: Tensor ("Const: 0", shape = (7,), dtype = float32) Input: [-1.5 -1. -0.5 0. 0.5 1. 1.5] Return type: Tensor ("log1p: 0", shape = (7,), dtype = float32) Output: [nan -inf -0.6931472 0. 0.4054651 0.6931472 0.91629076]

indicates that the natural logarithm 1 + x does not exist for negative values ​​and indicates that it approaches negative infinity when the input approaches -1.

Code # 2: Render

# Import Tensorflow library

import tensorflow as tf

 
# Import NumPy library

import numpy as np

  
# Import the matplotlib.pylot function

import matplotlib.pyplot as plt

 
# Vector size 20 with values ​​from -1 to 0 and from 0 to 10

a = np.append (np.linspace ( - 1 , 0 , 10 ), np.linspace ( 0 , 10 , 10 ))

 
# Applying a logarithmic function and
# preservation result in & # 39; b & # 39;

b = tf.log1p (a, name = `log1p` )

  
# Initiating a Tensorflow session
with tf.Session () as sess:

print ( `Input:` , a)

print ( ` Output: ` , sess.run (b))

  plt.plot (a, sess.run (b), color = `red ` , marker = " o " ) 

  plt.title ( " tensorflow.abs " ) 

plt.xlabel ( "X" ) 

plt.ylabel ( "Y" ) 

plt.grid ()

 

plt.show ()

Output :

 Input: [-1. -0.88888889 -0.77777778 -0.66666667 -0.55555556 -0.44444444 -0.33333333 -0.22222222 -0.11111111 0. 0. 1.11111111 2.22222222 3.33333333 4.44444444 5.55555556 6.66666667 7.77777778 8.88888889 10.] Output: [-inf -2.19722458 -1.5040774 -1.09861229 -0.81093022 -0.58778666 -0.40546511 -0.25131443 -0.11778304 0. 0. 0.7472144 1.17007125 1.46633707 1.69459572 1.88031287 2.03688193 2.17222328 2.29141179 2.39789527]