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Equation 15 · Part 7 · The Real Economics of Shipping a Model to a Device

fraction

Qdevice∗=Cdev+Uccloud−cd.Q^{*}_{\mathrm{device}} = \frac{C_{\mathrm{dev}} + U}{c_{\mathrm{cloud}} - c_{d}}.
fraction

What this part means

Divide the expression above the line by the one below it.

Its job in the formula

The expression above the fraction bar is divided by the complete expression below it. The denominator must not be zero.

The passage around this formula

and the break-even query volume — the point at which on-device placement stops costing more than cloud placement — is Qdevice∗=Cdev+Uccloud−cdQ^{*}_{\mathrm{device}} = \frac{C_{\mathrm{dev}} + U}{c_{\mathrm{cloud}} - c_{d}}. This is the same fixed-cost-against-marginal-cost structure that governs any make-versus-buy or capital-versus-operating-expense decision, and it is the structure Qualcomm’s marginal-cost claim silently assumes has already been paid off. Palkhiwala’s statement that an extra inference event is “effectively free” once the device is purchased is a claim about cdc_{d} alone; it says nothing about CdevC_{\mathrm{dev}} or U , both of which are paid by the model’s operator, not amortized into the price the customer already paid for the phone. Qualcomm’s own public…

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Learn the underlying idea

A fraction a/b means a divided by b. The top number is the numerator; the bottom number is the denominator, and it cannot be zero.

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Sources cited in the surrounding passage

These citations provide research context; check each source for the exact claim it supports.