CODEWITHSUNDEEP
matrix-multiplicationpytorchtensor
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Reputation: 31

Dot Product of Tensors with Different Shapes in PyTorch

p=torch.randn(2,3)
q=torch.randn(3,4,5)

I want to perform dot product, to obtain a result of shape (2,4,5).

How can this be done with PyTorch?

Upvotes: 0

Views: 2537

Answers (1)

benjaminplanche
benjaminplanche

Reputation: 15149

Two solutions for multi-dimensional matrix multiplications:

Demonstration:

import torch

p=torch.randn(2,3)
q=torch.randn(3,4,5)

# Solution 1: Reshaping to use 2-dimensional torch.mm()
res1 = torch.mm(p, q.resize(3, 4 * 5)).resize_(2, 4, 5)
print(res1.shape)
# torch.Size([2, 4, 5])

# Solution 2: Using explicit torch.einsum()
res2 = torch.einsum("ab,bcd->acd", (p, q))
print(res2.shape)
# torch.Size([2, 4, 5])

# Checking if results are equal:
print((res1 == res2).all())
# tensor(1, dtype=torch.uint8)

Upvotes: 3

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