PyTorch .lerp()
Published Oct 29, 2025
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In PyTorch, the .lerp() function computes the linear interpolation between an input tensor (input) and an end tensor (end), using a scalar or tensor weight. This is mathematically equivalent to applying the function $out_i = start_i + weight_i * (end_i - start_i)$.
The shapes of input, end, and weight must be broadcastable.
Syntax
torch.lerp(input, end, weight, *, out=None)
Parameters:
input: The input tensor containing the initial points.end: The ending tensor containing the finishing points.weight: The shapes of input, end, and weight must be broadcastable.out(optional): A tensor to store the output. If provided, the result is written to this tensor.
Return value:
Returns a new tensor containing the result given by the interpolation formula.
Example
The following example shows how to compute the interpolation between two tensors using torch.lerp() with a float scalar weight:
import torchimport math# Define two tensorsstart = torch.tensor([12.0 , 14.0 , 16.0 , math.log(2.)])end = torch.tensor([11.0 , 13.0 , 15.0 , math.log(2.)])# Compute the interpolation with a float weightout = torch.lerp(start, end, 0.8)print(out)
Here is the output:
tensor([11.2000, 13.2000, 15.2000, 0.6931])
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