torch.nn.CosineSimilarity

https://pytorch.org/docs/stable/generated/torch.nn.CosineSimilarity.html

import torch.nn as nn

input1 = torch.randn(100, 128)
input2 = torch.randn(100, 128)

sim = nn.CosineSimilarity(dim=1)(input1,input2)

# i.e.,
frac1 = torch.sum(input1*input2,dim=1)
frac2 = ((torch.sum(input1**2,dim=1)**0.5)*(torch.sum(input2**2,dim=1)**0.5))
sim = frac1/frac2