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Equation 3 · Part 2 · How Scientific Instruments and Metrology Actually Work

Symbol f

y=f(x1,x2,…,xN)y = f(x_1, x_2, \ldots, x_N)
ff

What this part means

f is an input to the expression that computes the quantity on the left.

Its job in the formula

f is an input to the expression that computes the quantity on the left.

The passage around this formula

The GUM’s central move is to treat every measured or estimated quantity a result depends on as a random variable with its own estimated standard uncertainty, and then to propagate those uncertainties through the mathematical relationship that produces the final result. If a measurement result y is a function of N input quantities, y = f(x1x_1, x2x_2, …\ldots, xNx_N) , the combined standard uncertainty is obtained from a first-order Taylor expansion of that function:

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Learn the underlying idea

A function assigns an output to each allowed input. The expression f(x) means “apply f to x”.

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See this notation across published equations →

Sources cited in the article section

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