Feat: Add .logical_not() term entry under tensor operations

content/pytorch/concepts/tensor-operations/terms/logical-not/logical-not.md

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+---
+Title: '.logical_not()'
+Description: 'Performs element-wise logical NOT on boolean tensors, returning a tensor where each element is the boolean negation of the input.'
+Subjects:
+  - 'AI'
+  - 'Computer Science'
+  - 'Data Science'
+  - 'Machine Learning'
+Tags:
+  - 'Booleans'
+  - 'Functions'
+  - 'PyTorch'
+  - 'Tensor'
+CatalogContent:
+  - 'intro-to-py-torch-and-neural-networks'
+  - 'paths/data-science'
+---
+
+In PyTorch, the **`.logical_not()`** function performs an element-wise logical negation on a [tensor](https://www.codecademy.com/resources/docs/pytorch/tensors). It returns a tensor where each element is `True` if the corresponding input is `False`, and `False` otherwise. For non-boolean tensors, zeros are treated as `False` and non-zeros as `True`.
+
+This function is commonly used in masking, boolean indexing, and creating complement conditions.
+
+## Syntax
+
+```pseudo
+torch.logical_not(input, *, out=None)
+```
+
+**Parameters:**
+
+- `input`: The input tensor containing boolean or numeric values.
+- `out` (Optional): A tensor to store the result. It must have the same shape as the output. The dtype is typically `torch.bool`, but integer types that can represent `0` and `1` (like `torch.int16`) are also supported. The results are stored as `1` for `True` and `0` for `False`.
+
+**Return value:**
+
+Returns a new tensor containing the element-wise logical negation of the input tensor.
+
+## Example
+
+The following example demonstrates the use of `.logical_not()` for masking and boolean inversion:
+
+```py
+import torch
+
+# Create a boolean tensor
+mask = torch.tensor([True, False, True, False])
+
+# Element-wise logical NOT
+inv = torch.logical_not(mask)
+
+print('mask:', mask)
+print('logical_not(mask):', inv)
+
+# Use logical_not to invert a condition from a numeric tensor
+vals = torch.tensor([0.0, 1.5, -2.0, 0.0])
+cond = vals > 0
+cond_inv = torch.logical_not(cond)
+
+print('\nvals:', vals)
+print('cond (vals > 0):', cond)
+print('cond inverted with logical_not:', cond_inv)
+
+# Numeric input — zeros are False, non-zeros are True
+print(torch.logical_not(torch.tensor([0., 2.45, -20., 3.8], dtype=torch.double)))
+
+# Using an integer out tensor (int16) to store 0/1 results
+out_buf = torch.empty(4, dtype=torch.int16)
+print(torch.logical_not(torch.tensor([0., 2.45, -20., 3.8], dtype=torch.double), out=out_buf))
+```
+
+The above code produces the following output:
+
+```shell
+mask: tensor([ True, False,  True, False])
+logical_not(mask): tensor([False,  True, False,  True])
+
+vals: tensor([ 0.0000,  1.5000, -2.0000,  0.0000])
+cond (vals > 0): tensor([False,  True, False, False])
+cond inverted with logical_not: tensor([ True, False,  True,  True])
+tensor([ True, False, False, False])
+tensor([1, 0, 0, 0], dtype=torch.int16)
+```