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| 1 | +--- |
| 2 | +Title: '.remainder()' |
| 3 | +Description: 'Computes the element-wise remainder of tensor division, where the result’s sign matches the divisor.' |
| 4 | +Subjects: |
| 5 | + - 'Computer Science' |
| 6 | + - 'Data Science' |
| 7 | +Tags: |
| 8 | + - 'AI' |
| 9 | + - 'Deep Learning' |
| 10 | + - 'Functions' |
| 11 | +CatalogContent: |
| 12 | + - 'intro-to-py-torch-and-neural-networks' |
| 13 | + - 'py-torch-for-classification' |
| 14 | +--- |
| 15 | + |
| 16 | +In PyTorch, the **`.remainder()`** function computes the element-wise remainder of division between two tensors or between a tensor and a scalar. The result always has the same sign as the divisor, unlike `.fmod()`, which matches the sign of the dividend. This operation works with both integer and floating-point tensors. |
| 17 | + |
| 18 | +## Syntax |
| 19 | + |
| 20 | +```pseudo |
| 21 | +torch.remainder(input, other) |
| 22 | +``` |
| 23 | + |
| 24 | +**Parameters:** |
| 25 | + |
| 26 | +- `input` (Tensor): The input tensor containing dividend values. |
| 27 | +- `other` (Tensor or Number): The divisor. It can be a scalar or another tensor of compatible shape. |
| 28 | +- `out` (Tensor, optional): The output tensor to store the result. |
| 29 | + |
| 30 | +**Return value:** |
| 31 | + |
| 32 | +Returns a tensor containing the element-wise remainder of the division. |
| 33 | + |
| 34 | +- If `other` is a scalar, the operation is applied using the same divisor for all elements. |
| 35 | +- If `other` is a tensor, element-wise division is performed. |
| 36 | + |
| 37 | +## Example 1: Divide a 1D Tensor by an Integer |
| 38 | + |
| 39 | +This example computes the remainder of each element in `x` when divided by 2, keeping the sign consistent with the divisor: |
| 40 | + |
| 41 | +```py |
| 42 | +import torch |
| 43 | + |
| 44 | +x = torch.tensor([-3, -4, -1, -6, 4, 7, 8]) |
| 45 | +print(torch.remainder(x, 3)) |
| 46 | +``` |
| 47 | + |
| 48 | +The output of this code is: |
| 49 | + |
| 50 | +```shell |
| 51 | +tensor([0, 2, 2, 0, 1, 1, 2]) |
| 52 | +``` |
| 53 | + |
| 54 | +## Example 2: Divide a 2D Tensor by an Integer |
| 55 | + |
| 56 | +In this example, each negative number wraps around within the range `[0, 4)` since the remainder must match the divisor’s sign: |
| 57 | + |
| 58 | +```py |
| 59 | +import torch |
| 60 | + |
| 61 | +A = torch.tensor([[ 1, 2, 3], |
| 62 | + [-1, -2, -3]]) |
| 63 | +print(torch.remainder(A, 4)) |
| 64 | +``` |
| 65 | + |
| 66 | +The output of this code is: |
| 67 | + |
| 68 | +```shell |
| 69 | +tensor([[1, 2, 3], |
| 70 | + [3, 2, 1]]) |
| 71 | +``` |
| 72 | + |
| 73 | +## Example 3: Divide a Tensor by Another Tensor |
| 74 | + |
| 75 | +This example demonstrates element-wise remainder calculation between two tensors of the same shape: |
| 76 | + |
| 77 | +```py |
| 78 | +import torch |
| 79 | + |
| 80 | +num = torch.tensor([ 3, -3, 3, -3], dtype=torch.int32) |
| 81 | +den = torch.tensor([ 2, 2, -2, -2], dtype=torch.int32) |
| 82 | +print(torch.remainder(num, den)) |
| 83 | +``` |
| 84 | + |
| 85 | +The output of this code is: |
| 86 | + |
| 87 | +```shell |
| 88 | +tensor([ 1, 1, -1, -1]) |
| 89 | +``` |
| 90 | + |
| 91 | +> **Note:** If `input` and `other` don’t share the same shape, PyTorch tries automatic size expansion (broadcasting). Dimensions match when they’re equal or one of them is 1 (aligned from the right). If no match is possible, a size-mismatch error is raised. |
| 92 | +
|
| 93 | +## Example 4: Divide a Floating-Point Tensor by a Number |
| 94 | + |
| 95 | +This example calculates remainders for floating-point values, preserving the sign of the divisor: |
| 96 | + |
| 97 | +```py |
| 98 | +import torch |
| 99 | + |
| 100 | +xf = torch.tensor([-7.5, 7.5, 5.0]) |
| 101 | +print(torch.remainder(xf, 4.0)) |
| 102 | +``` |
| 103 | + |
| 104 | +The output of this code is: |
| 105 | + |
| 106 | +```shell |
| 107 | +tensor([0.5, 3.5, 1.0]) |
| 108 | +``` |
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