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Equation 15 · Part 1 · The Real Economics of Shipping a Model to a Device

Symbol Q^*_device

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

What this part means

Qd∗Q^*_device is part of the quantity the equation computes from the expression on the right.

Its job in the formula

Qd∗Q^*_device is part of the quantity the equation computes from the expression on the right.

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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A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

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Sources cited in the surrounding passage

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