Bidirectional Scan for Vision

Vision Mamba processes image patches bidirectionally to capture both forward and backward context, unlike the causal (left-to-right only) scanning in language models.

For a 1D sequence $x = [x_1, x_2, ..., x_N]$:

• Forward scan: Cumulative sum from left to right
• Backward scan: Cumulative sum from right to left
• Output: Element-wise sum of forward and backward scans

This bidirectional approach ensures each patch attends to information from both directions, crucial for non-causal tasks like image classification.

Task: Implement the bidirectional scan fusion.