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The Indexing Formula

Under the hood, every 5D tensor is just a 1D list.

Key Insight​

PyTorch uses a simple math formula to find data in memory: flat_index = offset + Σ(index * stride). Mastering this formula demystifies how tensors actually work.

Why This Matters​

This formula is why PyTorch is fast. Knowing it helps you predict when operations will be efficient and why "non-contiguous" errors happen.