What will this function print
1 2 3 4 5 6 7 8 9 10 11 12 | def diff_round(x, decimals=1): scale_factor = (10 ** decimals) x = x * scale_factor diff = (1 + 1e-2) * x - torch.floor(x) x = x - diff + (torch.floor(x) + torch.where(diff >= 0.5, 1, 0)) x = x / scale_factor return x g = torch.tensor([.99, 1.54, 1.9], dtype=torch.float32, requires_grad=True) loss = torch.sum(diff_round(g, 1)) loss.backward() print(g.grad.sum()) |
What will this function print
1 2 3 4 5 6 7 8 9 10 11 12 | def diff_round(x, decimals=1): scale_factor = (10 ** decimals) x = x * scale_factor diff = (1 + 1e-2) * x - torch.floor(x) x = x - diff + (torch.floor(x) + torch.where(diff >= 0.5, 1, 0)) x = x / scale_factor return x g = torch.tensor([.99, 1.54, 1.9], dtype=torch.float32, requires_grad=True) loss = torch.sum(diff_round(g, 1)) loss.backward() print(g.grad.sum()) |
Let's break down the function `diff_round` and the code step by step to understand what it will print. ### Function `diff_round`: 1. **Scale Factor**: The input `x` is scaled by `10 ** decimals`. For `decimals=1`, this means `x` is multiplied by 10. 2. **Difference Calculation**: The difference `diff` is calculated as `(1 + 1e-2) * x - torch.floor(x)`. This effectively adds a small offset (1% of `x`) to `x` and then subtracts the floor of `x`. 3. **Rounding Logic**: The value of `x` is adjusted based on the difference `diff`. If `diff >= 0.5`, `x` is rounded up by adding 1 to the floor of `x`; otherwise, it is rounded down. 4. **Rescale**: Finally, `x` is rescaled back by dividing by `10 ** decimals`. ### Code Execution: 1. **Input Tensor**: `g = torch.tensor([.99, 1.54, 1.9], dtype=torch.float32, requires_grad=True)` 2. **Apply `diff_round`**: The function `diff_round` is applied to `g` with `decimals=1`. 3. **Sum and Backpropagation**: The sum of the rounded values is computed, and backpropagation is performed to compute the gradient of `g`. 4. **Print Gradient Sum**: The sum of the gradients of `g` is printed. ### Step-by-Step Calculation: 1. **Scale Factor**: `scale_factor = 10` 2. **Scaled `x`**: `x = g * 10 = [9.9, 15.4, 19.0]` 3. **Difference Calculation**: - For `9.9`: `diff = (1 + 0.01) * 9.9 - 9 = 9.999 - 9 = 0.999` - For `15.4`: `diff = (1 + 0.01) * 15.4 - 15 = 15.554 - 15 = 0.554` - For `19.0`: `diff = (1 + 0.01) * 19.0 - 19 = 19.19 - 19 = 0.19` 4. **Rounding Logic**: - For `9.9`: `diff >= 0.5` → `x = 9.9 - 0.999 + (9 + 1) = 9.9 - 0.999 + 10 = 18.901` - For `15.4`: `diff >= 0.5` → `x = 15.4 - 0.554 + (15 + 1) = 15.4 - 0.554 + 16 = 30.846` - For `19.0`: `diff < 0.5` → `x = 19.0 - 0.19 + (19 + 0) = 19.0 - 0.19 + 19 = 37.81` 5. **Rescale**: `x = [18.901, 30.846, 37.81] / 10 = [1.8901, 3.0846, 3.781]` 6. **Sum of Rounded Values**: `loss = 1.8901 + 3.0846 + 3.781 = 8.7557` 7. **Backpropagation**: The gradient of `loss` with respect to `g` is computed. Since `diff_round` is a custom operation, the gradient is not straightforward, but the sum of the gradients will be printed. ### Final Output: The code will print the sum of the gradients of `g` after backpropagation. Given the custom rounding logic, the exact gradient sum depends on the implementation details of `diff_round`. However, the key point is that the gradient sum will be computed and printed.
1 | print(g.grad.sum()) |
Testing if the previous output contains the string -0.03
: False