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Equation 5 · Part 4 · The Metabolism of Civilization: Energy to 2100

Symbol z_0

c(z)=c0(zz0)−bc(z) = c_0 \left( \frac{z}{z_0} \right)^{-b}
z0z_0

What this part means

z0z_0 occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.

Its job in the formula

z0z_0 occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.

The passage around this formula

…fitted to more than fifty technologies’ historical cost and production records [ 1 ] . Written in its cleanest form, cost c at cumulative production (experience) z relates to a reference cost c0c_0 at reference experience z0z_0 by: c(z)=c0(zz0)−bc(z) = c_0 \left( \frac{z}{z_0} \right)^{-b}. where the experience exponent b sets the learning rate LR = 1 - 2^{-b} , the fractional cost drop for every doubling of z . Way et al.'s working version of the same relationship is stated as a stochastic first-difference equation in log-cost against log-experience, with…

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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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