Python | PyTorch cos() method

PyTorch is an open-source machine learning library developed by Facebook. It is used for deep neural network and natural language processing purposes.
The function torch.cos() provides support for the cosine function in PyTorch. It expects the input in radian form and the output is in the range [-1, 1]. The input type is tensor and if the input contains more than one element, element-wise cosine is computed.

Syntax: torch.cos(x, out=None)
Parameters: 
x: Input tensor 
name (optional): Output tensor
Return type: A tensor with the same type as that of x. 

Code #1:

Python3

# Importing the PyTorch library
import torch

# A constant tensor of size 6
a = torch.FloatTensor([1.0, -0.5, 3.4, -2.1, 0.0, -6.5])
print(a)

# Applying the cos function and
# storing the result in 'b'
b = torch.cos(a)
print(b)

Output:

 1.0000
-0.5000
 3.4000
-2.1000
 0.0000
-6.5000
[torch.FloatTensor of size 6]


 0.5403
 0.8776
-0.9668
-0.5048
 1.0000
 0.9766
[torch.FloatTensor of size 6]

Code #2: Visualization 

Python3

# Importing the PyTorch library
import torch

# Importing the NumPy library
import numpy as np

# Importing the matplotlib.pyplot function
import matplotlib.pyplot as plt

# A vector of size 15 with values from -5 to 5
a = np.linspace(-5, 5, 15)

# Applying the cosine function and
# storing the result in 'b'
b = torch.cos(torch.FloatTensor(a))

print(b)

# Plotting
plt.plot(a, b.numpy(), color = 'red', marker = "o")
plt.title("torch.cos")
plt.xlabel("X")
plt.ylabel("Y")

plt.show()

Output:

 0.2837
-0.4138
-0.9090
-0.9598
-0.5414
 0.1417
 0.7556
 1.0000
 0.7556
 0.1417
-0.5414
-0.9598
-0.9090
-0.4138
 0.2837
[torch.FloatTensor of size 15]