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Equation 26 · Part 6 · How a Model Actually Gets Small Enough to Run on a Phone

subtraction

s=max⁡(∣x∣)2 b−1−1s = \frac{\max(|x|)}{2^{\,b-1} - 1}
subtraction

What this part means

Subtract the following term or group from the preceding one. A leading minus marks a negative quantity.

Its job in the formula

Subtract the following term or group from the preceding one. A leading minus marks a negative quantity.

The passage around this formula

For weights, a common simplification is symmetric quantization around zero, with z=0 and the scale set directly by the largest magnitude present: s=max⁡(∣x∣)2 b−1−1s = \frac{\max(|x|)}{2^{\,b-1} - 1}. for a signed integer of b bits. An 8-bit integer has 2^8=256 representable levels; a 4-bit integer has 2^4=16 . That sixteen-fold reduction in available codes is the entire cost of quantization in one number. Treating the rounding error as approximately uniform over one quantization step s , its expected squared magnitude is the classical result

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Learn the underlying idea

Addition combines quantities; subtraction measures the signed difference between them. Parentheses show what is combined before the rest of the expression is evaluated.

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Sources cited in the article section

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