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[GH-ISSUE #1154] [Module 2] GELU function hint typo #1710

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opened 2026-04-11 08:04:15 -05:00 by GiteaMirror · 0 comments
GiteaMirror commented 2026-04-11 08:04:15 -05:00
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Originally created by @oscarf189 on GitHub (Feb 4, 2026).
Original GitHub issue: https://github.com/harvard-edge/cs249r_book/issues/1154

1a80e57fa0/tinytorch/src/02_activations/02_activations.py (L618C1-L619C1)

This hint here says "The 1.702 constant comes from √(2/π) approximation", but √(2/π) = 0.79...

I believe that the 1.702 comes from the tanh used in the GELU paper, which approximates the function to be 0.5x(1 + tanh[√(2/π)(x + 0.044715x^3)... then the next line of the paper does mention the sigmoid approximation, but the number doesn't come from this?

In other words, maybe drop the hint? Or change the module to use tanh instead?

Originally created by @oscarf189 on GitHub (Feb 4, 2026). Original GitHub issue: https://github.com/harvard-edge/cs249r_book/issues/1154 https://github.com/harvard-edge/cs249r_book/blob/1a80e57fa07a5e551641df8db4dd2131524cb31f/tinytorch/src/02_activations/02_activations.py#L618C1-L619C1 This hint here says "The 1.702 constant comes from √(2/π) approximation", but √(2/π) = 0.79... I believe that the 1.702 comes from the tanh used in the GELU paper, which approximates the function to be 0.5x(1 + tanh[√(2/π)(x + 0.044715x^3)... then the next line of the paper does mention the sigmoid approximation, but the number doesn't come from this? In other words, maybe drop the hint? Or change the module to use tanh instead?
GiteaMirror added the type: improvementarea: tinytorch labels 2026-04-11 08:04:15 -05:00
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Reference: github-starred/cs249r_book#1710
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